To identify books, use the Advanced Search area of the Library's discovery system (or catalog), and especially, in decreasing order of specificity, its Subject, Title, and Any fields. For the electronic delivery of sections or chapters of books-on-paper owned by SPU, see Materials available via SPU Scanning. For e-books, Refine [your] results by Format: eBooks or Availability: Full Text Online:
Books unavailable via SPU and Summit Borrowing can be requested via Interlibrary Loan. Request an Interlibrary Loan from within a search of WorldCat (Libraries Worldwide). Unlike WorldCat, Harvard's Hollis is not (of course) linked up to InterLibrary Loan at SPU. That said, I find it easier to search than WorldCat.
Whereas Keywords will work anywhere, including in Title fields (and whereas official Subject headings will work as Keywords, too), only official Subject headings will work well in Subject fields. The official Subject headings for the book catalogs are given here: