Most of our e-books are in the UCSD's UC Library Search and you can find them by limiting results to Online only and Resource Types books.
Once you're in the e-book collection itself, you can browse by title or search the full-text of the entire collection.
In most collections, you can print/save desired chapters as PDF files. In other collections, you may have limited ability to save or print pages.
If we don't have an e-book you need, email Deborah and I'll see what I can buy for campus, You may also check Circuit for area San Diego libraries including SDSU, USD and public libraries or to get a print copy. Circuit service has resumed to UCSD as of June 2022; you may also use your SDPL or SDCL library card to get books delivered from area Circuit libraries to the branch library closest to UCSD or your house/apartment.
These are the main e-book collections (not single titles) of interest to math & stats researchers. Unless otherwise specified, books in these collections are also in the library catalog though the most recently published ones are generally available online 1-3 months before appearing in UC Library Search. Expect cataloging delays summer to fall 2021.
Search the full text of books scanned by Google, drawn from major libraries. The number of pages you can actually view varies, from the entire book for out-of-copyright titles, to snippets or selected pages for books still in copyright. If you find a book you want, use the library catalogs at UCSD and beyond to locate a copy.