The Catalog is the place to find books in the Princeton University Library. You can also use the catalog to find other materials, including videos, sound recordings, Internet sites, and journals (the journal subscription -- not individual articles).
Keyword searching is best used when you don't know the exact title, author's name, or subject heading. Use keywords especially when you want to discover what items the Library has for your topic, as this allows you to express the topic in your own words. For more tips on using the Catalog see the Help Page.
You can limit your search to just ONLINE content on the left-hand side under Access to find e-journals and ebooks. You should be able to request a scan of an article or book chapter from almost any book that the PUL only owns in print form.
Many databases index book reviews, including Articles+ and many subject databases that index the literature in/for a particular field. A lengthy book review can be a good source for learning enough about a particular title to warrant tracking it down or not as well as point to other authors and/or books on a similar theme.
To search for book reviews in Articles+, do a search, entering as many keywords as you'd like contained in the book title in question, and select Book Review under Content Type on the left-hand side.
Some general sources for book reviews:
There are other places to look for reviews, like the London Review of Books, New York Review of Books, New York Times Book, and H-Net Revies, all of which can be found under Databases on the library website. There's also the New York Times Book Review published on Sundays.