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Doing Research at the Library of Congress

IV. Keyword Searches

Sometimes there will be no formal subject heading that corresponds to the topic you have in mind. For example, a researcher interested in "memsahibs" (foreign women, usually British, in India's colonial period) could find no subject heading for that topic. Another researcher looking for material on "managing sociotechnical change" could also find no appropriate subject heading.

There are several ways to get around such problems. The first is to do keyword searches. These can be done not only in the Library's online catalog, but also in hundreds of commercial databases (covering books, journals, newspapers, dissertations, etc.) to which the Library subscribes. Internet search engines such as Google or Ask.com also work via keywords. The strength of this method of searching lies in its precision. The student looking for books or articles on "managing sociotechnical change" could instruct various databases to look for the exact word "sociotechnical" combined with the words "manag*" or "plan*" (the asterisk [*] being a truncation symbol); and she found numerous citations that had exactly the words she specified.

There are two big problems with keyword searches, however, that researchers need to take into account. The first is the problem of synonyms, variant phrases, and different languages. The trade-off with keyword searching is that its precise retrieval will miss variant words for the same topic. Thus a keyword search for "business blunders" will turn up articles with those exact words, but will miss others that have words like "corporate fiascos" or "management mistakes." Similarly, a search in an exclusively keyword database--i.e., one lacking controlled subject headings--on the words "death penalty" will miss all of the entries that use the phrases "capital punishment" or "legal execution." Keyword searching gives you exactly what you specify, and if the words you think of are slightly off, you may easily miss most of the relevant literature on your topic without realizing you've missed anything.

The second problem with keyword searching shows up especially in fulltext databases: keyword searching will very often overload you with irrelevant results that have the right words in the wrong contexts. (Some of these problems can be circumvented via phrase searching using quotation marks or other word-adjacency commands.)

In spite of its problems, however, there are situations in which keyword searching is the best available option. Among the hundreds of databases that allow keyword searches, several are particularly useful:

  • Digital Dissertations. The Library of Congress is the only library in the country (or the world) that owns a full set of American doctoral dissertations. They are not recorded in the regular online catalog, however. Searches must be done via this database instead; the UMI order numbers that it provides are used as the call numbers for the dissertations in the Microforms Reading Room.
  • Periodicals Index Online. This is a commercial database that indexes over 4,500 periodicals in forty languages from 1665 to 1995.
  • NTIS. The National Technical Information Service database is an index to over two million federally funded research reports produced since 1964. As with doctoral dissertations, the Library of Congress is the only library that has a full set of these research studies. They cover all fields of knowledge, with particular strengths in the hard and social sciences. The reports themselves are available through the Science Reading Room.
  • Web of Science. This is an index to over 8,500 scholarly journals, internationally. It translates the titles of foreign-language articles into English for keyword searches.

The Library also subscribes to many full-text commercial databases, among them Academic Search Premier, American Periodicals Series Online, Expanded Academic ASAP, InfoTrac OneFile, JSTOR, Project Muse, and ProQuest. These allow keyword searches, collectively, of articles in more than 15,000 electronic journals. (Note, however, that the large majority of the Library's 65,000 current periodical subscriptions are not available electronically; they can be read only in paper copy or microfilm formats.) Online listings of which electronic journal titles are available, through which subscription services, are provided by databases such as Serials Solutions, TDNet, and EZB.

A list of current database subscriptions is available on the Library's website. Please note that most of these resources are available only on Library premises. Consult the Library's reference staff for recommendations on databases relevant to your research. All of these databases allow keyword searches (some also allow searches by subject headings); and the list is continually growing.

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Doing Research at the Library of Congress
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  September 13, 2011
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