A thorough subject search of your topic is a great start to finding books in Princeton's online catalog. Some LC Subject headings have been provided here, but a complete listing of LC Subject Headings may also be found in pdfs online or in the catalog . You can also look up a known book on your topic and check the long view for the subject headings assigned to that book.
Richardson call numbers in Firestone (those that begin with four-digit numerals) have been converted to Library of Congress call numbers (which are alpha-numeric).
If the need arises to search a title with a Richardson call number, it is possible to search the Main Catalog for the title (as a "title") or the Richardson call number itself (as a "keyword") in order to obtain the current location and call number information.
