What are "Boolean operators?" If you search a catalog or database and receive a very large number of results, adding or limiting an additional keyword can help narrow your results and make your searches more useful. Boolean operators refer to the words "AND," "OR," and "NOT" (in capital letters) used in searches to either narrow or expand search results.
For example, a search for Japan AND literature will return items that contain both concepts:
poetry OR performance returns items that contain either one of the concepts or both:
Japan NOT China returns items that talk about Japan but do not mention China:
Subject headings
Subject headings are category words and phrases that group library resources together according to their main subject matter or genre. These are primarily useful for finding books and book-like items. (That is, they are less useful for finding articles, because the application of the terms is much more loose or uncontrolled.)
Finding subject headings
Look at a book record in Tripod, check the subjects assigned to it, and choose whatever ones are relevant for your research. These subject headings are provided by the Library of Congress and by our catalogers in the library.
For example, the book Ukiyoe: Images of Unknown Japan 
include a list of the following subjects.
If you click on one of these subject headings, it will give you a list of books that also share the same subject heading. Thus, "Ukiyoe" has 80 results.
Other sample subject headings
One extremely helpful feature within Google Scholar is that it links books and articles together if they have cited one another (to the extent the data they have allows).
