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Library and Information Science:
A Guide to Online Resources

Link disclaimerFrequently Asked Questions

People working at desks in the Main Reading Room of the Library of Congress
People working at desks in the Main Reading Room of the Library of Congress.
Photographic print,
between 1930 and 1950.
Prints and Photographs Division.
Reproduction Number:
LC-USZ62-100401

1. How do I find a book's Dewey Decimal classification number?
2. What do the different Library of Congress numbers mean?
3. How do I read a Library of Congress call number?
4. How do I organize my personal library or church library?
5. How do I automate my library?
6. How do I find a catalog record for a book?
7. How do I correlate a Dewey number with a Library of Congress call number or Library of Congress Subject Heading?
8. 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?

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

There is no comprehensive resource or database 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 up 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. You can search the catalogs of the public libraries 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 libraries are assigning a specific book.

2. 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.

3. 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

4. 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.

5. 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.

6. 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.

7. 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."

8. 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?

There exist several extensive book databases that allow users to retrieve bibliographic information based on an ISBN search. None of these databases is comprehensive, however. Examples of proprietary databases that allow retrieveal 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 permision 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

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 Team. Staff will be happy to refer your question to a Library expert.

 

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  April 3, 2008
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