

The Science of Subjects

Library of Congress Subject Headings

In the example on the previous page, "pet therapy" is considered natural language, searched as a keyword. The phrase "Pets - Therapeutic Use" used in the subject field is called controlled vocabulary.

Controlled vocabulary terms in the subject field all come from a set of books called the Library of Congress Subjects Headings, or LCSH. The LCSH (sometimes called the "red books") usually hang out near the reference desk.

Look up the words pet therapy in the LCSH and it will point you to the offiicial language, Pets - Therapeutic Use.


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