..DATABASES: LC Subject Headings

Subject headings provide one of the primary search techniques you may use in retrieving information from resources in the ISU Library. They may be used in both print and electronic sources. The strength of subject headings (often called descriptors) is that they allow us to use a controlled vocabulary to organize information in a logical fashion. The goal is to make it easier for you to find the specific information you need.

A controlled vocabulary is a set of standard terms used to describe the contents of items found in a database. This includes the contents of books in the library and articles listed in an index. A term in a controlled vocabulary may describe a person, an event, an idea, or a place.

In libraries we usually refer to the controlled vocabulary as subject headings. The ISU Library, in common with most academic libraries, uses the Library of Congress Subject Headings. This is a huge list of descriptive words and phrases which is published in four large, red volumes. Most of the records for books you will find in LUIS (the Libraries online catalog) have one or more subject headings attached to them. Periodical indexes often refer to their controlled vocabulary terms as descriptors, but it all means the same thing.

A controlled vocabulary is an important way of drawing together, under a single word or phrase, all the material that is available on a particular topic. The purpose is to take the "guess work" out of searching. We tend to have many different ways of describing the same concept. For example, let's say you're trying to find all the information you can in the library on the topic of the Civil War. What term would you use to search? Civil War? There have been a lot of those in many different countries. American Civil War? U.S. Civil War? United States Civil War? Civil War in the United States? War Between the States? War of Secession? War of the Rebellion? The Lost Cause? The choices are almost endless.

Does that mean you have to think up all these different synonymous terms in order to find everything you can on the topic? Not if you use a controlled vocabulary. For example, if you look up the term American Civil War in the Library of Congress Subject Headings you find that the subject heading to use is United States -- History -- Civil War, 1861-1865. That may seem a rather awkward or ponderous term to search, but using it will bring you a list of all the books the University Libraries have on the Civil War in a single search!

It's important to remember to check the subject heading books before searching. A subject search in LUIS on "Vietnam War", for instance, turns up only 47 entries, far fewer than one would expect on so important a topic. You must use the subject heading Vietnamese Conflict, 1961-1975 to find material on that subject. This search reveals 996 entries, which is more like it!

Periodical indexes, both print and electronic, also allow you to search for articles using a controlled vocabulary. For example, if you looked for articles on "freedom of religion" in a recent annual volume of the Social Sciences Index (a print index), you would be referred to the subject heading Religious liberty. Under that term you would find a list of all the articles on freedom of religion published during that year by the journals that the Social Sciences Index covers.

By drawing together all items on the same topic under a single word or phrase, a controlled vocabulary can make searching for information much easier.

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 the ISU Library Catalog, you must first determine the subject heading used for your topic.

Librarians at the Library of Congress in Washington DC 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

Finding the right subject heading

The first step in performing a subject search in the ISU Library Catalog 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 near the Reference Collection.

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.

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)

[DS79.72]

-- Mass media and the war

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 the ISU Library Catalog 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:

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.