Librarians organize information using controlled vocabulary. Books in most academic libraries are organized by Library of Congress Subject Headings (LCSH) in addition to author and title, and most subjects are subdivided by more specific subheadings. Not even your subject specialist librarians have memorized all of the LCSHs for their fields. If you don't know the LCSH for the topic you are searching, you can begin with a keyword ("Word(s)") search in the Classic Catalog. When you find a title that fits your topic, you can click on its record, find its LCSH ("Subjects"), and then click on that link to find all titles in the WUSTL libraries under that subject heading. Keep in mind, most books have multiple subject headings, and not all books which you might consider relevant to your topic will appear under the same subject heading. Below are links to some world history subject headings.