The Groundwater Project - Online Platform for Groundwater Knowledge
The Directory of Open Access Books (DOAB) - DOAB is a discovery service for peer reviewed open access books and book publishers that indexes and provides access to high quality, open access, peer-reviewed books.
OAPEN - OAPEN promotes and supports the transition to open access for academic books by providing open infrastructure services to stakeholders in scholarly communication.
Project Gutenberg - Project Gutenberg is a library of over 70,000 free eBooks