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Library of Congress Subject Headings

The ISU Library uses the Library of Congress Subject Headings (LCSH) as its "controlled vocabulary". This means that in order to perform a subject search in LUIS, the library's online catalog, you must first determine the subject heading used for your topic.

Librarians at the Library of Congress in Washington created this list of subject headings to describe the contents of materials in their collections. Development of the system began in 1898 and publication of the first edition began in 1909. New editions have appeared at regular intervals ever since to reflect historical developments and changes in society, technology, and terminology.

Although representing items held by the Library of Congress, most libraries use this same list to describe their own collections. The Library of Congress Subject Headings is such a huge list (currently published in four volumes) that it makes more sense to librarians to simply use this list rather than to "reinvent the wheel" by putting together their own list of subject headings. This also means that you may search a variety of different library catalogs on the Internet and use the same subject headings in each one. Thanks to LCSH we all, in a sense, speak the same language!

How to use LCSH

  1. Finding the right subject heading

    The first step in performing a subject search in LUIS is to figure out which subject heading represents your research topic. You may ask a librarian for help, or you may consult the Library of Congress Subject Headings books yourself. These large, red volumes are available next to the LUIS terminals just past the main entrance.

    How do you describe your topic? What word or phrase best describes that topic to you? Look up that word or phrase in LCSH. If your term is not the correct heading, LCSH should provide a cross reference from your term to the subject heading.

    For example, let's say we want to find material relating to the Gulf War. If we open the LCSH volume that includes the letter "G" and look up the term "Gulf War" we find the following entries:

      Gulf War, 1980-1988

    • USE Iran-Iraq War, 1980-1988
      Gulf War, 1991
    • USE Persian Gulf War, 1991

    The notation "USE" tells us to search under the term Persian Gulf War, 1991 if we want information on the conflict in which the United States was directly involved. At this point we can search LUIS for our topic, or we can look up our subject heading in LCSH to see if more information is available.


  2. Entries for Subject Headings

    Entries for subject headings in LCSH often provide useful information that may help you in locating relevant material in LUIS. For example, you may be able to identify other subject headings to use in searching.

    Here is the entry for Persian Gulf War, 1991:

      Persian Gulf War, 1991 (May Subd Geog)


        UF Desert Storm, Operation, 1991
        Gulf War, 1991
        Operation Desert Storm, 1991
        War in the Gulf, 1991
        BT Iraq -- History -- 1958-
        Persian Gulf Region -- History
        United States -- History, Military -- 20th century
        RT Iraq-Kuwait Crisis, 1990-1991
        -- Mass media and the war
        UF Persian Gulf War, 1991, in mass media [Former heading]
  3. Interpreting Entries in LCSH

    Let's take a look at the above entry from LCSH. Each element provides us with potentially useful information.

    Valid subject headings always appear in boldface type. This immediately tells us that Persian Gulf War, 1991 is a subject heading.

    The italicized phrase (May Subd Geog) tells us that we may use the names of countries or regions as subheadings. This means that if we're interested primarily in American involvement in the Gulf War, we may search using the subject heading: Persian Gulf War, 1991 -- United States.

    The bracketed call number [DS79.72] tells us that items concerning the Gulf War are usually shelved under that number. If you like browsing the bookshelves (a research strategy known as serendipity!) this identifies the place in the library you will find most books related to this topic.

    Terms listed after the notation UF are terms synonymous with the subject heading. This means that the term Persian Gulf War, 1991 is Used For (i.e. used instead of) identical terms such as "Gulf War" or "Operation Desert Storm". Even though these terms are not valid, searchable subject headings, don't ignore them. You may wish to use them in a keyword search in LUIS or another computer database, such as an index.

    The BT notation indicates Broader Topics. LCSH has a thesaural format with a hierarchy of terms ranging from those that cover very broad topics (e.g. the whole history of the Persian Gulf Region) down to very narrow topics (such as a single conflict in the region). Terms listed beside a BT notation are always valid, searchable subject headings.

    The notation RT identifies Related Topics that provide access to information in some way relevant to our subject heading. In this case the crisis that began with Iraq's invasion of Kuwait in 1990 is related to the war that followed. Searching under the subject heading Iraq-Kuwait Crisis, 1990-1991 may lead us to other useful material.

    When you encounter a word or phrase in an entry that is printed in boldface and preceded by a hyphen, you have a "subheading" or "subdivision" of the main subject heading. Subheadings allow us to combine two or more concepts into a single subject heading. In the example above, we would search under the term Persian Gulf War, 1991 -- Mass media and the war if we wanted material specifically related to the way the war was covered on television or in the press. Notice that subheadings may also have UF, BT, NT and RT notations. In our example, the heading Persian Gulf War, 1991 -- Mass media and the war is now used instead of the former (but no longer used) heading "Persian Gulf War, 1991, in mass media".

    A final notation not listed under this subject heading is NT. This indicates the existence of Narrower Topics. (Remember that hierarchical format!) If we look up the subject heading Nursing in LCSH we find the following:

      NT Aviation nursing
      Geriatric nursing
      Maternity nursing
      School nursing

    There are are about 25 or so terms listed, but you get the idea. NT simply identifies specific aspects of the topic covered by the subject heading you're looking at. In this case, different aspects of nursing. Again, this is designed to help you identify useful search terms. Each term listed with an NT notation is a valid, searchable subject heading

NOTE:  If you can't decide on the subject heading to use or you don't find anything on your topic with a subject search, try the search again as a keyword search. You may get a very different result!

This is only a very brief introduction to the Library of Congress Subject Headings. If you have any problems or questions, please ask one of the librarians working at the Reference Desk for assistance.  You may also use the form for Online Questions and Comments  or chat online with a Reference Librarian at Reference Live.

Revised October 2, 2001

ACKNOWLEDGEMENTS: This page is adapted from the McFarlin Library Web site at The University of Tulsa, and is kindly used with their permission.

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