www.openscholarship.org
Provides background information, data and guidance material on open scholarship-related issues, including a comprehensive section on open access, in both French and English.
www.openoasis.org
Reference guide about open access covering the concept, principles, approaches, developments and initiatives from around the world. In English.
www.open-access.net
Overview of Open Access in German and English with country specific information for Switzerland and soon, for Austria.
opcit.eprints.org/oacitation-biblio.html
Bibliography of studies on the effects of Open Access on citation impact