A project by the Wikimedia Foundation.
A collection of open-content textbooks that anyone can edit.
- https://en.wikibooks.org/wiki/Main_Page (english)
- https://de.wikibooks.org/wiki/Main_Page (german)
- https://en.wikibooks.org/wiki/Wikibooks_portal (other languages)
Also see: List of largest wikibooks
Related: Wikimedia Foundation, Wikipedia, Project Gutenberg