Proquest Ebook Central
Over 140,000 scholarly ebooks available covering a wide range of topics. These books are all in WorldCat Discovery but using this site allows you to search for terms within the full text of the books.
Oxford Scholarship Online
Titles published 2016-present from Oxford University Press. Multidisciplinary, including History, Law, Literature, Neuroscience, Philosophy, Political Science, Public Health, and Religion. These books are all in WorldCat Discovery but using this site allows you to search for terms within the full text of the books.
Search the full text of millions of books digitized by Google from major academic libraries. Most pre-1923 texts are available in full and can usually be downloaded as pdf files.
Hathi Trust Digital Library
Nearly 4 million titles and over 6 million volumes digitized by major research libraries. Many of the titles are the ones digitized by the Google Books project but the collection also includes many non-Google titles. Intended for use by academic researchers.
A project of the Internet Archive which contains nearly 2 million full-text ebooks. A smaller collection than Google Books or Hathi Trust but it sometimes has volumes unavailable elsewhere.