The Library Catalog is a database of Penn's online and print books, videos and similar material (articles are excluded). Although not as simple as Amazon, for example, it is powerful once you learn simple tricks.
Keyword Expert searching
By using the Keyword Expert option to combine related terms, you can easily expand and narrow your search. For example, if you are interested in the relationship between Nietzsche and German Fascism then this search would be useful: nietzsche AND (fascism OR nazi* OR hitler). AND and OR must be capitalized.
Subject Headings and Subject Heading Browse
When you find a book that is particularly relevant to your interests, look at the subject headings, which will direct you to similar books. Also, when you find a subject heading with many subheadings, browse through them to identify many categories of books related to the main subject heading.
Use the Library link to access Google Scholar in order to view proprietary resources. Use the "Cited by" function to find works that cite a book or article that is especially relevant to your research.