Fluctuation of total collagen, type Ⅰ and Ⅱ collagen protein contents in the knee joint of osteoporotic rats 
Zhao Liang-jun, Peng Fen-fen, Zhuang Wei, Tang Xiao-zheng
Chinese Journal of Tissue Engineering Research . 2011, (2): 205 -207 .  DOI: 10.3969/j.issn.1673-8225.2011.02.004