Keyword and subject searches are two different things, and both are part of an effective strategy for searching databases:
1. Begin with a keyword search by entering words that describe the information you are seeking.
2. Once you have some results, look at the records to see what subject headings the database uses.
3. Revise your search using the appropriate subject terms.
Subject headings provide a standard vocabulary for describing the content of materials. The UNC-Chapel Hill Library Catalog uses the Library of Congress (LC) Subject Classification System. Other databases may use different subject systems. Unlike keywords, the terms that you use in a subject search must match the exact format of the subject headings.
Here are some examples of Library of Congress subject headings in mathematics: