The Library of Congress Subject Headings, or “Red Books,” as they were known back in the card catalog days, have a long history of usage in libraries. They provide a controlled vocabulary that often, but not always, matches subject terms used in keyword searches. They provide a system of references which give other terms a library user may wish to consult, and links from terms not used in the Library of Congress subject thesaurus to those that are. This system of references can be a big help, especially in detailed research.
Some library users recoil at the thought of searching for material using the Library of Congress Subject Headings. Used shrewdly, they can be a big help. Start the search with a single term. Library users will, for example, search “Contracts – United States.” This is fine, but if you search simply “Contracts” you will find a list of related terms which can help you now and in the future.
An “exciting” example can be viewed here: Exciting example
Broad subject terms, such as “Property” or “Torts,” almost always have related terms attached to them. Browsing these will provide useful terms you can use in further searching. Consider adding the name of a state or country to them to locate material you may wish to consult. It helps to be curious.
For further information ask a reference librarian to see the Red Books, or view them online.