Using designated Subject headings from The Library of Congress can help find relevant materials more effectively (both for books in the library and articles in the databases). You can often create correct subject headings by following them as a model. Some examples of subject headings for film history:
Motion Pictures - History
Silent Films - History
Documentary Films - History and Criticism
Motion Pictures - Spain - Chronology
Micheaux, Oscar, 1884-1951 - Criticism and Interpretation