Most disciplines have subject-specific reference works.
These works provide an overview or introduction to an issue, an event, a person, or phenomena. This is often a good place to start to narrow or broaden a topic. Most often general information is an introductory article or chapter in an encyclopedia or dictionary or handbook . Consult the Library of Congress Subject Heading books to gather keywords to use when searching for your topic. To combine two or more search terms, use an Advanced Search.