Collombat, P., Hecksher-Soerensen, J., Serup, P., & Mansouri, A. (2006). Specifying pancreatic endocrine cell fates. Mechanisms of Development, 123(7), 501-512. Retrieved from http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T9H-4K1V497-5-5&_cdi=5115&_user=38661&_orig=browse&_coverDate=07%2F31%2F2006&_sk=998769992&view=c&wchp=dGLbVzW-zSkzS&md5=6bf3e05742cf1c4791c61731a4f97bba&ie=/sdarticle.pdf.