OAPEN: Open Access Publishing in European Network
OAPEN is a very wonderful resource for open access books. It contains freely accessible books on society and social science, humanities, Economics, Finance, Business, Management, Law, Art, Language & Literature, Earth Science, Geography, Environment and Plannings.
The OAPEN Foundation is a non-profit foundation dedicated to Open Access publishing of academic books. OAPEN provides a platform for the full text dissemination of Open Access books and provides services to publishers and libraries. OAPEN builds a quality controlled collection of Open Access books
To search the OAPEN online library follow the link
http://www.oapen.org/search