Stem Cells Portal, 15 Dec 2011 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022550
Stem Cells Portal, 25 Jul 2011 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022550