Franklin Catalog is your guide to books here at Penn Libraries. Searching by subject heading (the topic of the book) will yield the best results, once you have identified the subject heading of interest. Some useful subject headings include:
WorldCat will be a valuable resource for searching the catalogs of other libraries. WorldCat can be searched using the same subject headings you used in Franklin. If you find something not held at Penn, you may request it via Interlibrary Loan, Borrow Direct or EZBorrow.
Every research question will require different databases for the literature search, depending on the questions asked. In addition to general databases like Google Scholar, JSTOR, or Scopus, consider these specialized databases for the relevant field.