It is usually more efficient to start with a keyword search and use the results to discover the Subject Headings listed in the book records. The Subject Headings will be hot-linked to take you to similar results.
Uses natural language. The search engine will search the book record for those words in the title, author, subject headings and table of contents.
Requires precise, specific Library of Congress Subject Headings. The words have to be typed in the exact order used by Library of Congress
Examples of Library of Congress Subject Headings