Liu, Hai-Xia; Huang, Guo-Rui; Zhang, Huan-Ming; Wu, Jia-Rui; Yao, Zhu-Jun Bioorganic and Medicinal Chemistry Letters, 2007, vol. 17, # 12 p. 3426 - 3430 doi: 10.1016/j.bmcl.2007.03.084