Controlled vocabularies help solve the problem of access points .
A controlled vocabulary is simply a limited set of subject descriptor words. All access tools incorporate some type of controlled vocabulary. Sometimes a summary or listing of the controlled vocabulary for an access tool is available. For an example, see the Library of Congress Subject Headings . Indexes that rely exclusively on controlled vocabulary for subject access also provide see and see also references which guide you to the appropriate subject heading or to related or more specific subject headings.