Effect of enamel matrix derivatives on the differentiation and proliferation of human periodontal ligament stem cells 
Wang Shuang, Feng Pei-xun, Chen Yue, Zhang Hai-juan, Li Sha, Bao Qing-hong, Guan Li-min
Chinese Journal of Tissue Engineering Research . 2015, (23): 3716 -3722 .  DOI: 10.3969/j.issn.2095-4344.2015.23.019