Gallica, the digital library of the Bibliothèque Nationale de France (BnF), includes digitized texts, still images, and sound recordings. The BnF site also includes access to some electronic periodicals and Mandragore, a database that gives access to the library's collection of medieval illuminated manuscripts.
Access note: Freely available to the public.
You can search Google Books or HathiTrust to find published books online. If it was published before 1923, you have a good chance of finding the entire book online.
Immense, continuously updated digital collection providing enhanced search and availability of millions of public domain, in-copyright, and permissioned digitized books, federal government documents and serial publications in a variety of languages from sources such as Google Books, Internet Archive, Microsoft and initiatives at partner academic and research institutions.
Access note: Freely available to the public. Current DePaul faculty, staff and students get extra functionality when logged in such as full PDF downloads of public domain and permissioned works and options to create and share content collections. To log in, click the LOGIN button and select DePaul from the list.