BASE is a multidisciplinary search engine for scholarly internet resources which have been harvested from several hundred scientific repositories. Some of the indexed resources in BASE are subject to license, while most material is free available ("open access").

Google Book Search is a service from Google that searches the full text of books that Google scans, converts to text using optical character recognition, and stores in its digital database.

The Max Planck e-Book Index provides holdings of electronic books licensed for users in the Max Planck Society.