Databases are multidisciplinary collections of scholarly resources. Most databases gather links to and citations for scholarly articles, although some contain additional information on books and other resources.
These resources will help you find e-books and print held by Notre Dame, other local libraries, or books held at other libraries worldwide. If you can't find a book at Notre Dame or its partner libraries in the ND Catalog, try searching the catalogs of 9000 OCLC partner institutions through Worldcat. The Hathi Trust is another sizeable consortial collection of digitized books.
Bibliographies gather together various resources focused around specific subjects, sub-topics, fields, etc. They are an important and efficient way to begin a review of scholarly literature.
These resources will help you find unpublished theses and dissertations, which present an author's research and findings as part of their degree candidacy or professional qualification.