As explained in the reading on Subject Headings, you should always closely check "cross references" ("See" and "See also" references) and "tracings" (subject headings listed for specific articles, books or other documents) to try to find useful subject headings for a topic. But even when you use these strategies, sometimes you may not be able to find the best subject headings for a topic.

"Controlled Vocabulary" Lists

The most comprehensive tool for finding subject headings for any topic in a periodical index or library catalog is the official subject heading list for that index or catalog. These subject heading lists are sometimes referred to as an "authority file" or a "controlled vocabulary" list. Most indexes or catalogs use some form of "controlled vocabulary" so that indexers (the people who assign subject headings to each record) have a standardized list of headings to choose from for each article, book or other document. Researchers can use this same list to find the right search terms for their topic. Controlled vocabularies for many indexes are available in book form and, for most online databases they can be accessed electronically.

The most useful controlled vocabulary lists, called "thesauri" ("thesaurus" is the singular form,) include broader, narrower, and related terms, as well as indications of headings not used. Thesauri are very useful to researchers because they:

One of the most extensive and commonly-used controlled vocabulary lists is the Library of Congress Subject Headings (LCSH), which is used by most library catalogs. This list is available in a five-volume set of large red books, usually found near the catalog or reference desk in most libraries. You can also access most of the LCSH information at the Library of Congress web site by using the Subject search mode of the Library of Congress catalog. The LCSH is described below.

Many of the major academic abstracting databases (discussed in the "Periodicals" section), such as Psychological Abstracts, Sociological Abstracts and the ERIC education abstracts, publish printed thesauri, which have formats relatively similar to LCSH.  

Library of Congress Subject Headings (LCSH) Using the Library of Congress Web Catalog

Most of the subject heading information of the LCSH is available by using the Subject search mode of the Library of Congress web catalog (link to: [See example]

When you enter a subject word or words in the box and click the Search button (or press Enter), a "Headings List" will be displayed in four columns [See example]:

To use this search mode to find useful subject headings for your topic, look for an entry related to your topic with the icon and click on this icon to view any of the following:

Follow any of the links listed for a topic you are researching in order to collect as many official subject headings as you can find that might be relevant to your subject. You can then use these subject headings when searching for books and other information on your subject in library catalogs or other research databases. You do not need to display the specific items listed for any of the subject headings in the Library of Congress. The purpose for using this database is simply to find useful subject headings for your further research.

*Note: A "0" (zero) in the Titles column means that no catalog records use the heading; instead users should click on to link to the heading actually used for the subject. [See example]

Library of Congress Subject Headings (LCSH) Print Version

In the print version of the LCSH, terms used as subject headings are printed in boldface type. Sometimes Library of Congress classification letters and numbers are listed after a subject heading. This classification information indicates the beginning letters and numbers of call numbers for books specifically on that subject. (For more information on LC classification, see the section on Library of Congress Call Numbers). Occasionally a scope note is included after a subject heading. A scope note is a short paragraph defining what information is included under the given subject heading.

Several different types of cross reference terms are used in the LCSH. Each type of term is described below:

USE: When a word is listed in regular print and is immediately followed on the next line by the term USE, the word listed above the "USE" is not a correct subject heading. A USE reference in the LCSH is the same as a SEE reference in a catalog. For example:

Travel and health
USE Travel--Health aspects

The USE reference here redirects the researcher from a term that is not used (Travel and health) to one that is used (Travel--Health aspects).

UF: USED FOR indicates headings that are not used. In general, UF references should be ignored when you are using the LCSH to find related subject headings. UF references simply indicate that USE references have been made from these unused headings to the heading in boldface type above them, which are used.

The following three types of cross references are similar to SEE ALSO references in a catalog. In addition to simply indicating other subject headings that are related to a given heading, each of these references describes how the terms are related in scope:

BT: BROADER TERM indicates headings for related topics that are broader in scope.

RT: RELATED TERM links two terms that are related in some way, but equal in scope.

NT: NARROWER TERM indicates headings for related topics that are narrower or more specific in scope.

An additional cross reference also identifies related subject headings, but is used less frequently:

SA: SEE ALSO indicates a related term that is listed as a subheading of other terms.

SUBHEADINGS of used subject headings are listed after all of the cross references for the heading. Subheadings are indicated with a single dash (-). Further subdivisions of subheadings are indicated with additional dashes. All of the cross references described above may also be used for any subheadings. The abbreviated note "(May subd Geog) " following a subject heading indicates that geographical subdivisions may be used with that heading. Form subheadings may be used with any subject heading and are not included in the LCSH.

General guidelines to follow when using the LCSH to find related subject headings:

Look up USE references to find headings that are used for a subject; then look up BT, RT and NT references as appropriate. RT references should be especially noted since they are most equivalent to the given subject heading. NT references should be used when you need to narrow your topic. Subdivisions (subheadings) should also be used to find more specific headings on a subject. Broader terms should be used if your topic seems to be too specific and you have not been able to find enough information.

Since the LCSH is based on the Library of Congress collection, which is one of the largest library collections in the world, many valid subject headings will only be found in the largest or most specialized library catalogs and will not be included in most library catalogs.


Continuing with my preliminary research on the control and influence of mass media, I look up "mass media" in the LCSH. Since Mass media is listed in bold print, I know it is a proper LC subject heading. The note in parentheses: "(May Subd Geog)" means that this subject heading may be subdivided geographically, that is there can be subheadings of mass media for any geographic area (eg. countries, states, cities.) Immediately under the entry for Mass media is a scope note-- a brief definition of the use of the term by LC and how some related concepts are classified. I note that "Works on the communications industries treated collectively are entered under Communication and traffic." This tells me that the subject heading, "Communication and traffic" is another heading to check since it the subject of the communications industries is related to my topic.

Below the definition is "UF Mass communication." This indicates that "Mass communication is not a used subject heading and that "Mass media" is the correct subject heading to use instead. The next line, "BT Communication," identifies one subject heading that is broader in scope than "Mass media."

Following the one broader term is a long list of terms classified as "NT", subject headings that are narrower in scope than "Mass media." This list starts with "Africa in mass media" (figure A, bottom of column 2) and continues onto the next page ending with "Zaire in mass media." Reading through this list, I don't find any subject headings that seem directly related to my topic; but I do note several headings that may be interesting aspects to focus in on if I find that I need to narrow my topic further. "Collective bargaining--Effect of mass media on", "Trade-unions and mass media" and "Women in the mass media industry" are all headings that may help provide further focus for my research.

After the list of narrower terms, the subheadings of "Mass media" begin with "--Audiences" . The bold print indicates that "Mass media--Audiences" is a used subject heading. Directly below this subheading is "P96.A83." This is the LC call number assigned to this subject heading. In make a note of this subheading since it seems like it might relate to my topic. Another heading that might cover information related to my topic is "Mass media--Social aspects," which is listed under the broader terms for this subheading.

Slightly lower down the list of subheadings is "--Employees," another used subheading of "Mass Media." Immediately below this subheading is "-- --Trade-unions." The two dashes indicates that this would be a subheading of a subheading. Since it is not in bold print, however, it is not a used heading. The correct heading to use for this is "Trade-unions--Mass media" as is indicated by the next line that begins with the reference: "USE."

As I scan through the rest of the subheadings, I note some others that might be related to my topic: "--Law and legislation" and "--Political aspects." I also note two other subheadings that seem related to my topic, "--Evaluation" and "--Government policy." These headings are not used, however, but the "USE" references refer me to other headings, "Mass media criticism" and "Mass media policy," respectively.

The most appropriate search terms vary depending on which access tools are used in the search. When searching for books in a library, the basic research tool is the catalog, and the LCSH lists proper subject headings for most catalogs. When searching for periodical articles, however, there is a wide range of databases from which to choose. Each database may have its own controlled vocabulary list. As you list search terms for your topic, then, it is important to identify those terms which are used in the specific databases in which you are planning to search. Use the controlled vocabulary list which corresponds to the database being used.

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last revised: 2-6-00 by Eric Brenner, Skyline College, San Bruno, CA

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