1. Directory of Elsevier open access journals. Available at http://www.elsevier.com/about/open-access/open-access-journals. Accessed April 27, 2013.
2. Open access to the scientific journal literature: situation 2009;Bjork;PLoS One,2010
3. Free journals grow amid ongoing debate;Kaiser;Science,2010
4. Open access journals: why are we not there yet? (!);Gores;Hepatology,2010
5. Crossref.org. History/mission. Available at http://www.crossref.org/01company/02history.html. Accessed April 27, 2013.