Library and Information Science:
A Guide to Online Resources

Frequently Asked Questions

1. What classification system does the Library of Congress use?
2. How do I find a book's Dewey Decimal classification number?
3. What do the different Library of Congress numbers mean?
4. How do I read a Library of Congress call number?
5. How do I organize my personal library or church library?
6. How do I automate my library?
7. How do I find a catalog record for a book?
8. How do I correlate a Dewey number with a Library of Congress call number or Library of Congress Subject Heading?
9. Is there an International Standard Book Number (ISBN) database I can use that will allow me to extract bibliographic data for books and import them into a local database?
10. What type of Integrated Library System does the Library use?
11. What are the major milestones in the history of the Library's Web site and online presence?
12. Does the Library make the full text of books available on its Web site?
13. Where can I find full-text books online?
14. Are records for all of the titles listed in the print National Union Catalog (NUC) now available through the Library of Congress online catalog and WorldCat database?
15. How can I search copyright registration and renewal records online?
16. Why are the letters I, O, W, X, and Y not used in the Library of Congress Classification?
17. How do I tell whether a book is poetry or prose? Does the Library of Congress indicate this in its catalog records?
18. How do I tell whether a book is fiction or nonfiction? Does the Library of Congress indicate this in its catalog records?
19. What is the difference between an ISBN-10 and an ISBN-13? Is there a tool to convert between these numbers? Does the Library's online catalog support searching for ISBN-10s and ISBN-13s?
20. Is the Book of Secrets from National Treasure 2 a real book?
21. How much data is represented by the Library's physical and digital collections?

1. What classification system does the Library of Congress use?

The Library of Congress classifies books according to the Library of Congress Classification (LCC) system. An outline of LCC is available on the Library's Web site. The complete text of the classification schedules in printed volumes may be purchased from the Cataloging Distribution Service. Online access to the complete text of the schedules is available through Classification Web, a subscription product that may also be purchased from the Cataloging Distribution Service.

2. How do I find a book's Dewey Decimal classification number?

There is no comprehensive resource or database that you can check to locate a book's Dewey decimal number. The best place to begin your search is the Library of Congress Online Catalog. When you open a record for a book in the catalog, click on the Full Record tab at the top of the page and look for a field labeled "Dewey Class No." If this field is listed, it will give the book's Dewey classification.

Unfortunately, while many Library of Congress catalog records contain Dewey numbers, the majority do not. The Library generally assigns Dewey numbers to nearly all U.S. trade imprints--including all titles cataloged in the Cataloging in Publication (CIP) program, children's literature, and to many books in English, French, German, Italian, Spanish, and Portuguese.

If you don't find a book's Dewey number through the Library's online catalog, another resource you can use to locate it is OCLC's WorldCat database. WorldCat functions as a collective catalog of thousands of libraries around the world. A subscription version of WorldCat is available at some public and many academic libraries, while a free version is available on the Web at http://www.worldcat.org. The subscription version of WorldCat will often provide the Dewey class number (the first part of the Dewey number) for a book, and both the subscription and free versions list libraries known to hold copies of a book. Search the catalogs of the public libraries that WorldCat lists as holding a copy of a book to see if any have assigned the book a Dewey number. The numbers may vary slightly from one library to another based on local guidelines and standards, but they will give you an idea of the Dewey numbers that libraries assign a specific book.

3. What do the different Library of Congress numbers mean?

There are several Library of Congress numbers which users often conflate. They are:

Library of Congress Control Number (LCCN)

A Library of Congress Control Number (LCCN) is a unique identification number that the Library of Congress assigns to the catalog record created for each book in its cataloged collections. Librarians use it to locate a specific Library of Congress catalog record in the national databases and to order catalog cards from the Library of Congress or from commercial suppliers. The Library of Congress assigns this number while the book is being cataloged. Under certain circumstances, however, a card number can be assigned before the book is published through the Preassigned Control Number Program.

What is now known as the Library of Congress Control Number was originally known as the Library of Congress Card Number until the advent of machine-readable records for book materials in the late 1960s.

An LCCN can have one of two different structures, based on when it was assigned:

89-456 (numbers assigned before 1/1/2001)
2001-1114 (numbers assigned after 1/1/2001)

In addition, LCCNs for some items cataloged before 2001 may include an alphabetic prefix:

GM 69-509
sn 82-6058

In the Library's online catalog, LCCNs are reformatted to remove hyphens and standardize character length. To see what reformatted LCCNs look like, and to find instructions for searching the Library's online catalog by LCCN, go here.

Library of Congress Call Number

A Library of Congress call number is a unique number assigned to items in the Library's collections that represents the item in the Library's online catalog, identifies the specific copy of the item in the collections, and gives its relative location on the shelf. Library of Congress call numbers are assigned by Library catalogers based on the the Library of Congress Classification (LCC) system.

For information on the structure of LC call numbers, and how to read them, see FAQ #3.

Copyright Registration Number

A unique number assigned to all works registered with the U.S. Copyright Office at the Library of Congress. The copyright registration number is typically formatted as two or three letters (depending on the classification) followed by one to seven digits. Examples include:

SR-320-918
VAu-598-764
TX-4-323-103

Preassigned Control Number

A Preassigned Control Number (PCN) is a Library of Congress Control Number which has been "preassigned" to a given work prior to the work's publication. Works are assigned a PCN through the Preassigned Control Number Program.

International Standard Serial Number (ISSN)

The International Standard Serial Number (ISSN) is an eight-digit number which identifies all periodical publications as such, including electronic serials. Most countries have an ISSN National Center responsible for assigning ISBNs to serials. In the United States, ISBNs are assigned by the National Serials Data Program at the Library of Congress.

Users sometimes confuse the following numbers with a Library of Congress number:

International Standard Book Number (ISBN)

The International Standard Book Number (ISBN) was approved as ISO standard 2108 in 1970. It is a 10- or 13-digit number that uniquely identifies books and book-like products published internationally. The Library of Congress does not assign ISBNs to books. Instead, there are over 160 ISBN Agencies worldwide, each of which is appointed as the exclusive agent responsible for assigning ISBNs to publishers residing in their country or geographic territory. The United States ISBN Agency, R. R. Bowker, is the only source authorized to assign ISBNs to publishers supplying an address in the United States, U.S. Virgin Islands, Guam, and Puerto Rico and its database establishes the publisher of record associated with each prefix. Review the ISBN FAQ for further information.

Universal Product Code (UPC) Number

Also known as a bar code. The UPC number is a string of digits that typically appears on the back of books (and other consumer products). The UPC number appears in association with a machine-readable code that appears as a series of black and white strips or bars. In the United States, UPC numbers are assigned to products by the organization GS1 US. An overview of the UPC can be found on the HowStuffWorks Web site.

4. How do I read a Library of Congress call number?

A number of academic institutions have created guides on how to read Library of Congress call numbers. See the following Web sites for excellent LC call number overviews:

"Understanding Library of Congress (LC) Call Numbers," American Museum of Natural History Research Library

"Finding a Book on the Shelf--Library of Congress Classification," Colorado State University Libraries

"Understanding Call Numbers," Honolulu Community College Library

"How to Read Call Numbers," University of California Berkeley, Kresge Engineering Library

5. How do I organize my personal library or church library?

The American Library Association's Fact Sheet Number 16, Setting Up a Library: A Resource Guide, compiles print and online resources for individuals interested in organizing their libraries. See especially the sections on home and family libraries and church and synagogue libraries.

Melissa L. Rethlefsen's January 15, 2007, Product Pipeline article in Library Journal reviews a number of booksharing Web sites, some of which enable users to catalog their personal libraries.

Additional tools for cataloging a small and personal libraries can be found through the Google Directory.

6. How do I automate my library?

For an overview of library automation issues, see the American Library Association's Fact Sheet Number 21, "Automating Libraries and Virtual Reference: A Selected Annotated Bibliography," which "offers a selection of articles, treatises, and web resources that will provide an introduction to the issues to consider when moving from the card catalog to the computerized catalog, or upgrading from one present integrated library system (ILS) to another, or considering implementing virtual reference services."

Library Technology Guides, prepared by Marshall Breeding (Jean and Alexander Heard Library, Vanderbilt University), includes a database of library automation companies you can use to find companies that develop and market library automation systems.

Every April, Library Journal publishes a review of the current library automation marketplace. For the 2009 review, see the article "Investing in The Future: Automation Marketplace 2009."

7. How do I find an online catalog record for a book?

Three major types of online catalogs make catalog records for books available to the public: local library catalogs, national library catalogs, and union catalogs.

Local Library Catalogs

A local library catalog, such as the catalog for a public library or an academic library, contains records for items held by a single library. To find out what items are held by your local public library, you can search its online catalog, if one is available. The following two Web sites can help you identify your local library, and whether it may have a Web site or an online catalog.

lib-web-cats

A directory of more than 5,000 libraries around the world. Includes links to each library's Web site and online catalog.

LibDex

An index to more than 18,000 libraries' Web sites and online catalogs.

National Library Catalogs

National library catalogs are much larger than local library catalogs. A national library typically includes an extensive, if not comprehensive, collection of works published in a given country, and its catalog provides a primary access point to these items. Examples of online national library catalogs are:

Library of Congress Online Catalog

British Library Integrated Catalogue

National Library of China Online Public Access Catalogs (select NLC Online Catalogs link)

Other national library catalogs are listed by the University of Queensland Library.

Union Catalogs

Union catalogs are catalogs which list the holdings of multiple libraries. These catalogs can be used to identify which libraries hold a particular item. Two of the most important online union catalogs are:

The European Library

The European Library is a free service that offers access to the resources of the 47 national libraries of Europe in 20 languages. Resources can be both digital and bibliographical (books, posters, maps, sound recordings, videos, etc.).

WorldCat

WorldCat is the largest union catalog in the world, providing access to nearly 100 million bibliographic records that represent more than one billion items and the holdings of more than 10,000 libraries around the world. Using WorldCat, you can discover which libraries nearest you hold an item you'd like to access. See WorldCat's About page for additional information.

8. How do I correlate a Dewey number with a Library of Congress classification number or Library of Congress Subject Heading?

A subscription database known as Classification Web provides correlations between Dewey and Library of Congress classification numbers, as well as between these call numbers and Library of Congress Subject Headings. You can check with your local library to see if it has access to this database.

A print resource which provides a similar function, though not as comprehensively, is the 3rd edition of Mona L. Scott's 3-volume Conversion Tables (v. 1, LC-Dewey; v. 2, Dewey-LC; v. 3, Subject Headings-LC and Dewey).

A very general classification conversion tool, available for free online, is provided on OCLC's reference management service QuestionPoint. See the following two pages:

Map LC (LCC) to Dewey (DDC) Classification

Map Dewey (DDC) Classification to LC (LCC)

These pages note that "mappings to LCC classes D, J and K are still in process. LCC Class R has been replaced, in QuestionPoint, by National Library of Medicine (NLM) Classes QS-QZ and W. Most NLM Classes map to 362.1-362.3 and 610-618.97."

9. Is there an International Standard Book Number (ISBN) database I can use that will allow me to extract bibliographic data for books and import them into a local database?

Several extensive book databases allow users to retrieve bibliographic information based on an ISBN search. None of these databases is comprehensive, however. Examples of proprietary databases that allow retrieval of bibliographic information for books based on ISBN are the subscription database Books in Print and the database freely available online through the commercial vendor Amazon.com (see its Advanced Search page). To see if it is possible to configure the information in these databases for your needs, and to obtain permission to do so, you will need to contact and obtain the permission of the vendor.

While the Library of Congress generally cannot provide technical support services for individuals creating their own catalogs or databases, the Library of Congress online catalog allows users to search for and retrieve catalog records based on ISBNs. If you would like to use the information in the catalog to develop a Web-based application that captures bibliographic information based on an item's ISBN, the Library supports a Web service that allows users to retrieve catalog records in XML. In order to take advantage of this service, known as SRU (Search/Retrieval via URL), users must have the ability to display the XML data in the format they desire. Below are some examples of SRU requests that retrieve the same record from the Library's catalog (via its Z39.50 interface). The final two examples make use of XSLT style sheets created by the Library. Users can also develop their own style sheets and retrieve the raw XML records using requests similar to the first one listed below.

SRU Request Examples

• Retrieves record in MARCXML
• Retrieves record in MODS schema
• Retrieves record in Dublin Core schema
• Retrieves record in OPACXML schema (i.e., MARCXML with holdings)
• Brief display with LC "branding"
• Full MARC tagged display

Please note that the Library of Congress online catalog does not include a record for every book published in the United States. Furthermore, not every book receives an ISBN. A number of other libraries' catalogs are also available using the Z39.50 protocol. Many are listed on the Library's Z39.50 gateway.

Another solution is to use a batch search facility that allows Library of Congress catalog records to be exported into a desired format, or provides you with a tool set that you can use to create style sheets to perform the desired conversion. Two such batch search facilities (which are both present in Z39.50 clients) are:

MarcEdit (free)

Includes a batch search mode. The input file can be a file of ISBNs, ISSNs, titles, or other data (and one can customize a search using YAZ search syntax). The output is a file that contains all of the records that were retrieved from the target database using the input file. For more information about this tool, please consult the MarcEdit online tutorials.

BookWhere (for fee)

Includes a batch search mode. BookWhere functions much the same as MarcEdit.
Users construct the input file the one search term per line. BookWhere, however,can convert the output file to a number of formats: text, tabbed text, Reference Manager, Ibidem, Citation 7/8, Refer, InMagic, ProCite, EdiBase, XML, HTML, MARCXML, Dublin Core.

Information about other, similar tools may be found on the Library’s MARC Specialized Tools Web site.

While accessing a data set from the Library's database using tools such as those mentioned above, please instruct your software to pause for 5-10 seconds between every ten records to allow other users access to it.

If you have further questions, please contact the Digital Reference Section. Staff will be happy to refer your question to a Library expert.

10. What type of Integrated Library System (ILS) does the Library of Congress use?

In May 2008, the Library upgraded its ILS to Voyager version 6.5.2 from Ex Libris.

A contract for the Library's first ILS was awarded on May 15, 1998, to Endeavor Information Systems, Inc., for its Voyager integrated library system. On October 1, 1999, the Library successfully completed initial implementation of all modules of the ILS, including cataloging, circulation, acquisitions, serials check-in modules, and the online public access catalog.

For further information about the Library's Integrated Library System, see the Library's ILS Program Office home page, background page, and FAQ.

11. What are some of the milestones in the Library's use of the Internet to share its resources with the public?

The Library of Congress has explored and taken advantage of the Internet's potential for sharing the Library's content with remote users since the early 1990s. The following timeline highlights significant moments in the history and development of the Library's presence online.

(Note: All quotations in the timeline are from the article "The National Digital Library and the Library's Electronic Resources" in the Encyclopedia of the Library of Congress)

1990

• Remote Online LOCIS User Pilot (ROLLUP), an experimental project with fourteen state library agencies and the D.C. Public Library, provides remote access to library databases
• The American Memory pilot project offers selected primary source materials from its Americana collections to schools and libraries through CD-ROMs. The five-year project (1990-94) culminates in the establishment of the National Digital Library Program and the American Memory Web site.
• LC establishes its first Internet connection through UNIX-based servers housed in its IT department

1991

• LC DIRECT, an outgrowth of ROLLUP and a fee-based service to 33 state library agencies, provides remote online access to the Library's bibliographic databases beginning in January

1992

• LC's first online exhibition, Revelations from the Russian Archives, available on the Internet through FTP
• Following the success of LC's first online exhibition, additional information related to the Library's reading rooms, hours, special collections, services to the blind, and copyright registration procedures added online
• The Library of Congress News Service, a source for information about the Library's programs, exhibits, activities, hours of operation, and job openings, launches in October. Enables computer users to dial in to the service over telephone lines by using modems connected to their personal computers.

1993

• LOCIS, the Library of Congress Information System (available through TELNET), debuts online to the public in April. Provides access to "the Library's catalog, the status of legislation since 1993, abstracts of laws from several Hispanic-speaking countries, braille and audio materials and copyright registration records since 1978."
• LC MARVEL (Machine-Assisted Realization of the Virtual Electronic Library) debuts in June at the American Library Association conference and becomes available to the public in July. A bulletin-board service, it provides "a wide variety of information about the Library, including information about events and jobs as well as images and text from the Library's exhibitions and links to a vast collection of Internet resources worldwide."
• The Newspaper and Current Periodical Reading Room opens the Library fist public work station with Internet access in June 1993
• LC establishes in-house support for electronic discussion lists (LISTSERVs) in July. The Library's only prior LISTSERV (USMARC-L), established in June 1991, was hosted through the University of Maine.

1994

• LC Web site debuts at the annual ALA conference in Miami, Florida, June 22-30
• National Digital Library Program launches on October 13, with American Memory made available online as its flagship project
• LC's National Reference Service (NRS) begins a pilot project to respond to reference queries received over the Internet at the email address lcref@loc.gov (no longer active) on November 7. Many questions are referred by NRS to email accounts maintained by other areas of the Library.

1995

• THOMAS legislative Web site debuts on January 5
• Z39.50 Gateway installed on the Library's Web site, making it possible for Internet users to search the Library's online bibliographic database (MUMS) and other catalogs
• The Newspaper and Current Periodical Reading Room creates the first LC reading room home page on the World Wide Web
• During the summer, the National Reference Services establishes lcinfo@loc.gov (no longer active), a centralized Internet email address for online inquiries to LC
• Federal Research Division country studies first become available online

1996

• LC's Learning Page debuts on March 6
• The Ameritech Foundation announces it will make a $2 million gift to establish the Library of Congress/Ameritech National Digital Library Competition. This three-year competition (1996-1999) open to public, research, and academic libraries, as well as museums, historical societies, and archival institutions (with the exception of federal institutions), produced 23 digital collections in American Memory.
• LC home page redesigned on July 6
• GLIN (Global Legal Information Network) debuts on the Library's Web site in July
• Library offers its first online chat conference via an AOL public chat room on October 17: "1492: An Ongoing Voyage." Issues were explored and questions and comments from participating AOL-subscribers were addressed by the Library's Senior Specialist in Hispanic Bibliography, Dr. John Hebert, the curator of the 1992-1993 exhibition. Staff from the National Digital Library Program facilitated the program.
• LC's online catalog becomes available through the Web
• Library offers free Internet access on ten workstations in five LC reading rooms and the Computer Catalog Center

1997

• Today in History debuts on April 1

1998

• The Prints and Photographs Online Catalog debuts

1999

• LC Web home page redesign debuts on January 25 (see before and after)
• The National Reference Service is incorporated into the Humanities and Social Science Division and renamed the Reference Referral Service
• Places in the News debuts in April
• The Meeting of Frontiers Web site, the first component of the International Horizons project (later renamed Global Gateway), debuts. It is the first bilingual project on the Library's Web site.
• Web-Braille, which allows braille readers to read more than 2,700 books files in digital braille, debuts in August
• LC's new ILS online public catalog becomes available on the Web on August 31

2000

• America's Library Web site debuts on April 24
• The Collaborative Digital Reference Service (CDRS) pilot project goes live on June 29, 2000. The CDRS software is a precursor to QuestionPoint, which will become the software used by the Library to manage its Ask a Librarian service.
• The National Digital Information and Preservation Program (NDIIPP) created by congressional legislation on December 20

2001

• Library hosts live public Web conference on April 3, with mystery author Sara Paretsky, using the LSSI Virtual Reference Desk software's chatroom feature
• Portals to the World debuts
• Videoconference programs and workshops to assist participants in navigating, searching, and accessing materials in the Library's online collections, begin in September
• The Digital Reference Section is created in November to provide reference services related to the Library's online collections

2002

• Poetry 180 debuts on January 4
• LC home page and top tier pages redesigned in June (see before and after). Lower tier pages redesigned later in the year.
• The Wise Guide debuts on October 12
• LC's Ask a Librarian service using QuestionPoint software debuts in June
• Veterans History Project debuts online. The National Registry of Service (now the Veterans History Project database) debuts on November 11.

2003

• LC MARVEL migrated to HTML pages and retired
• LC acquires its first major digital collection, the September 11 Digital Archive, on September 10

2004

• LC offers its first public Web conference, "Armchair Traveler," through Online Programming for All Libraries (OPAL) on August 24

2005

• LC redesigns top-tier Web pages in April (see before and after)
• LC joins Internet2 and offers first Internet2 videoconference program

2006

• Performing Arts Encyclopedia Online debuts on May 26
• A beta federated search application debuts on LC's home page on October 16
• LC's first RSS feeds debut on December 18
• First podcasts made available on LC's Web site

2007

• Chronicling America, the National Digital Newspaper Program Web site of historical newspapers, debuts on March 21
• LC's first public blog debuts on April 24

2008

• LC's Flickr pilot project made available to the public
• myLOC.gov debuts on April 12
• electronic Copyright Office (eCO) registration system debuts on July 1
• E-Giving Web site for Library donations debuts on July 30
• LC's wireless network begins rollout

2009

• LC launches Twitter feed on January 27
• LC's YouTube channel, created June 9, 2007, opens to the public on April 7
• LC, UNESCO, and partner institutions launch the World Digital Library on April 21
• LC Launches new Teachers Page on June 25 (formal launch occurred June 30)
• LC launches "The Library of Congress on iTunes U" on June 30

12. Does the Library of Congress make full-text books available on its Web site?

Except for very rare instances, full text books cannot be found on the Library's Web site. Full-text books that are available tend to be older publications published prior to 1923 that are no longer under U.S. copyright protection. Academic textbooks and recent works of fiction cannot be found on the Library's Web site, and recent nonfiction on the site is limited to Library of Congress publications such as annual reports, illustrated collection guides, Federal Research Division country studies, and a history of the Library of Congress. If you want to obtain a recent work of fiction or nonfiction not available through your local library, you should contact your library and ask staff there to place interlibrary loan request for the book with another library.

13. Where can I find full-text books online?

There are numerous organizations that provide access to full-text books online, though at present most free online books tend to be older materials no longer covered by copyright. Some publishers provide electronic versions of contemporary books, but unless you are able to access them through a public or university library subscription, there is usually a fee involved.

Several Web sites that have created extensive listings of online book resources follow:

Digital Book Index

Provides access to more than 100,000 free full-text books--and more than 142,000 total online books--from over 1800 commercial and non-commercial publishers, universities, and various private sites. Free registration required.

The Internet Public Library: Online Texts

A compilation of major online resources for free full-text books and poems.

The Online Books Page: Archives and Indexes

A large compilation of online literature resources on the Web. Includes sections on general-purpose collections with substantial English-language listings (large-scale repositories; significant indexes and search aids; and significant smaller-scale archives), foreign language and literature resources, and specialty archives.

14. Are records for all of the titles listed in the print National Union Catalog (NUC) now available through the Library of Congress online catalog and WorldCat database?

Although a search of OCLC's WorldCat database and the Library of Congress online catalog retrieves many records listed in the print editions of the National Union Catalog, a number of records are still unavailable. A 2005 article in College & Research Libraries, "The Proportion of NUC Pre-56 Titles Represented in OCLC WorldCat" (PDF, 441 KB), estimated that 27.8% of NUC Pre-1956 records were not listed in WorldCat. It is unlikely that WorldCat has reached 100% inclusivity in the intervening years, making a search of NUC an important supplement to WorldCat.

In addition, due to the manner in which the retrospective conversion of the Library's old card catalog to online form was undertaken, NUC continues to include some entries for works in the Library's collections not listed in the Library's online catalog. Consequently, it should be consulted in any thorough examination of the Library's resources.

15. How can I search copyright registration and renewal records online?

There are several databases you can search to locate copyright registration and renewal records online. The only official database as this time is the U.S. Copyright Office Catalog; the others listed below represent the work of individuals and organizations not affiliated with the U.S Copyright Office at the Library of Congress.

U.S. Copyright Office Catalog (original records and renewals, 1978-present)

The U.S. Copyright Office's Copyright Office Catalog makes available approximately 20 million records for works registered and documents recorded with the Copyright Office since 1978. Please note that it takes several months for a work submitted to the U.S. Copyright Office to be fully processed and added to this catalog.

The Online Book Page's Catalog of Copyright Entries Page (renewal records, 1950 - 1977)

This Web page from the University of Pennsylvania's Online Books Page makes available scanned images for copyright renewal records for books and other texts originally registered for copyright between 1922-1950. In addition, this page links to additional online resources for finding copyright registrations and renewal records for written texts.

Selected Copyright Renewal Registrations, 1950-1977

Transcriptions of copyright renewal registrations from 1950-1977 provided by Project Gutenberg. These renewal registrations cover books and other texts originally registered for copyright between 1922-1950.

Stanford University's Copyright Renewal Database (renewal records, 1950-1992)

This database "makes searchable the copyright renewal records received by the US Copyright Office between 1950 and 1992 for books published in the US between 1923 and 1963. Note that the database includes ONLY US Class A (book) renewals."

These databases will not always provide definitive information on the copyright status of a work. Further information on researching the copyright status of works can be found through the U.S. Copyright Office, Circular 22, "How to Investigate the Copyright Status of a Work" (PDF, 232 KB), and the Online Books Page feature, "How Can I Tell Whether a Copyright Was Renewed?"

16. Why are the letters I, O, W, X, and Y not used in the Library of Congress Classification?

The Library of Congress Classification (LCC) consists of 21 main classes, each class represented by a letter of the alphabet. Because only 21 classes were required to represent the major subject areas and disciplines classified by the Library, five letters were not included as part of the LCC. The reason that the particular letters I, O, W, X, and Y were not selected for the LCC is a matter of some debate. There are few extant records that document the development of the LCC, and it appears that none which survive discuss why these letters remained unused.

Despite the lack of documentation, an oral tradition passed down through generations of Library of Congress catalogers accounts for the exclusion of these letters from the LCC. This tradition holds that the letter I was not used because it is too similar to the number 1; use of an I class would cause confusion for people looking for works which had a call number such as I1, I10, and I111. Similarly, the letter O was not selected because it is indistinguishable from the number 0 (zero). W, X, and Y, as the final letters of the alphabet (not including Z), were never needed since there were only 21 classes. Had there been a 22nd class, perhaps W would have been the next letter used, and if there had been a 23rd class created thereafter, perhaps X. The letter Z was chosen as a class rather than W, X, or Y in part because it is the symbolic end of the alphabet. In addition, the Library's Class Z is based upon a Class Z (Book Arts) developed earlier by Charles Ammi Cutter for his Expansive Classification system. Somewhat ironically, Class Z was the first Library class created, prepared in 1898 by Charles Martel.

17. How do I tell whether a book is poetry or prose? Does the Library of Congress indicate this in its catalog records?

The Library of Congress does not explicitly indicate whether a book is poetry or prose in its catalog records. You can review the Library of Congress Subject Headings (LCSH) assigned to a book to see whether a word such as poetry or biography, which might help indicate the form of the book, is given. Bear in mind that a subject term such as poetry is typically used designate a prose work about poetry (e.g., a collection of essays), and not a work of poetry itself. The Library of Congress Classification cannot be used to determine whether a book is poetry or prose; however, a book's Dewey Decimal number, which is often available through Library catalog records, will sometimes indicate the form of a book's content. Once you learn a book's Dewey number, you can review the heading describing the topic that the number represents through the Dewey Decimal Classification Summaries. For instance, the following numbers for American and British literature help to indicate whether a work is poetry or prose:

811 American poetry in English
813 American fiction in English
821 English poetry
823 English fiction

Other options for determining whether a book is prose or poetry include checking the physical book, especially its back and front covers, spine, and copyright page, and dust jacket, to see if the publisher has included a designation of poetry or a nonfiction genre; consulting book reviews, articles, and other publications about the work to see if they mention its format; checking the book publisher's or author's Web site to see if it indicates the form of the book; contacting the book's publisher (contact information is usually available through the Web); and contacting the book's author (through his or her publisher, an official Web site or social networking page, or other means).

The Library receives many questions about whether a work is poetry or prose from Texas students and teachers participating in University Interscholastic League (UIL) speech and debate competitions. An excellent UIL document that assists with this process is "Defining and Distinguishing Poetry, Prose, and Drama." The UIL's FAQ page and other areas of its Web site discuss appropriate and inappropriate forms of documentation for contests and who to contact for an official ruling in uncertain cases.

If you'd like to receive the Library's help determining whether a book is poetry or prose, please use the Digital Reference Section's Ask a Librarian Web form.

18. How do I tell whether a book is fiction or nonfiction? Does the Library of Congress indicate this in its catalog records?

Library of Congress catalog records do not always provide a definitive answer to whether a work is fiction or nonfiction. Ascertaining whether a book is fiction or nonfiction through the the Library's online catalog is usually performed through review of the Library of Congress classification number assigned to a book. To find the classification number assigned to a book, you can search the online catalog to find a record for the book in question, then click on the Full Record tab and review the field labeled LC Classification. (You should also review any Library of Congress Subject Headings listed on this page, as they may provide a designation of fiction.) Literature is classified under the letter P, but there is wide variation on whether something in Class P is fiction or nonfiction. If you find that the Library of Congress classification number starts with PZ, that is definitely fiction. PR and PS (English and American Literature, respectively) can be used for works of fiction, as well as works of nonfiction such as literary criticism, essays, biographies of authors, etc. You would need to look at the full classification number and at a very detailed classification schedule for help in determining if it is fiction or nonfiction, and this may not be conclusive. These extended classification schedules are not currently available online for free, though they can generally be found at college and university libraries. The Library often is asked about works with a classification of PN: sometimes these are collections of wit and humor. In this case, the Library of Congress classification will not designate whether the work is fiction or nonfiction, and it may be necessary to use other means to make a determination.

To see whether other Library classes identify a work as fiction or nonfiction, you can check other class numbers against the descriptions of them given in the Library of Congress Classification Outline. For instance, for a book classified as HV, one can use the classification outline to learn that this is a designation for social sciences and the work is, therefore, nonfiction.

A book's Dewey Decimal number, which is often available through Library catalog records, will sometimes indicate whether a book is fiction or nonfiction. Once you learn a book's Dewey number, you can review the heading describing the topic that the number represents through the Dewey Decimal Classification Summaries. For instance, the following numbers for literature indicate the work is fiction:

813 American fiction in English
823 English fiction
833 German fiction
843 French fiction

Other options for determining whether a book is fiction or nonfiction include checking the physical book, especially its back and front covers, spine, and copyright page, and dust jacket, to see if the publisher has included a designation of fiction or nonfiction; reviewing bestseller lists, book reviews, articles, and other publications about the work which may mention its genre; checking the book publisher's or author's Web site to see if it indicates the genre of the book; contacting the book's publisher (contact information is usually available through the Web); and contacting the book's author (through his or her publisher, an official Web site or social networking page, or other means).

The Library receives many questions about whether a work is fiction or nonfiction from Texas students and teachers participating in University Interscholastic League (UIL) speech and debate competitions. Participants should explore the UIL's Web site, including "Prose/Poetry FAQ," "Prose Rules," "Helpful Checklist for UIL Prose Documentation Requirements" (PDF, 88 KB) and FAQ page to learn about appropriate and inappropriate forms of documentation for contests and who to contact for an official ruling in uncertain cases.

19. What is the difference between an ISBN-10 and an ISBN-13? Is there a tool to convert between these numbers? Does the Library's online catalog support searching for ISBN-10s and ISBN-13s?

On January 1, 2007, the book industry began using 13 digit ISBNs to identify all books in the supply chain. The U.S. ISBN Agency notes that this change was effected to "expand the numbering capacity of the ISBN system and alleviate numbering shortages in certain areas of the world"; and "to fully align the numbering system for books with the global EAN.UCC identification system that is widely used to identify most other consumer goods worldwide."

An ISBN-13 differs from an ISBN-10 through the inclusion of three-digit prefix (978 or 979) and a different check digit (final digit) at the end. Conversion tools are available to convert ISBN-10s to ISBN-13s (and vice versa) and to calculate an ISBN's check digit. Please note, however, that ISBN-13s beginning with the prefix 979 have no ISBN-10 counterparts.

The Library of Congress Online Catalog automatically converts between ISBN-10s and ISBN-13s, ensuring that any ISBN search will check for both an ISBN-10 and an ISBN-13. For example, if a catalog record includes only an ISBN-10, a search for the equivalent ISBN-13 will retrieve the record.

20. Is the Book of Secrets from National Treasure 2 a real book?

The Book of Secrets is not an authentic historical book. The Book of Secrets is a fictitious prop created for the movie National Treasure: Book of Secrets. This movie prop was loaned to the Library of Congress by Disney and displayed from July 1 to September 27, 2008, in the South Orientation Gallery on the first floor of the Thomas Jefferson Building.

There are, of course, real secrets that presidents are made aware of during their terms of office, mostly relating to military matters and national security. The National Archives and Records Administration keeps extensive records of investigations such as that regarding the Kennedy assassination (allegedly contained in the movie's Book of Secrets). Many of these records are "classified" and not open to the public, at least for a certain period of time, but records of that sort would involve thousands of pages of documents and be managed by archivists with security clearances, not neatly contained in a single volume that could be passed from one president to another. One sort of secret that is passed from one president to another, however, is described in a USA Today article, "Military Aides Still Carry the President's Nuclear 'Football.'"

21. How much data is represented by the Library's physical and digital collections?

Matt Raymond, Director of Communications at the Library of Congress, provides an overview of how much data the Library's physical and digital content represents on the Library of Congress blog. Mr. Raymond notes that, as of February 11, 2009, "the approximate amount of [the Library's] collections that are digitized and freely and publicly available on the Internet is about 74 terabytes. We can also say that we have about 15.3 million digital items online."

Please note that where Mr. Raymond mentions "15.3 million digital items online," he means, more specifically, files. A single item can consist of multiple files, and the ratio between the numbers of catalog records, physical objects, and digital files that represent a single item can vary considerably, depending largely on the type of physical objects and how they have been cataloged, scanned, and presented on the Library's Web site. Here are some examples to illustrate this point:

• A book in American Memory has one item record. (There might also be one record for a multi-volume set, or one record for each article in a bound journal.) This "item" might be represented by one SGML file, and perhaps converted to HTML. It might also be represented by three progressively higher-definition image files for each page; have images only for its illustrated pages; or have only images and no transcriptions or a transcription and no images.
• The architectural study of the White House in Washington, D.C. has one record representing 757 physical objects (including photographs, architectural drawings, and documents), which, in turn are represented by 3028 files (GIF, JPEG, TIFF and higher resolution TIFF files).
• The kinetescope of a sneeze, a motion picture from Thomas Edison's studio, has one record representing one physical object. This object, in turn, is represented by two digital files (MPG and QuickTime).
• Items in American Memory collections from "partner institutions" may be represented on the Library of Congress servers as only an item record with thumbnail images and a link to a server elsewhere. This is the case, for example, with the sheet music from the collection Historic American Sheet Music, 1850-1920, for which the image files reside on a server at Duke University.