Books can provide a comprehensive overview of your topic by pointing you towards key ideas, arguments, and thinkers. Scan the index or the table of contents to find the most relevant chapter. Use the bibliography for more leads.
Subject headings are maintained by the Library of Congress and applied to sources to make them discoverable. Try using them in a subject search in conjunction with keywords derived from your topic.
Here's an example of subject headings as they appear in the library catalog:
Can't find a way to work Blade Runner into your research on ancient Greek philosophy? No problem! There are subject headings for any topic you can imagine.