Cao, Xin; You, Qi-Dong; Li, Zhi-Yu; Liu, Xiao-Rong; Xu, Dan; Guo, Qing-Long; Shang, Jing; Chern, Ji-Wang; Chen, Meng-Ling Bioorganic and Medicinal Chemistry Letters, 2008 , vol. 18, # 23 p. 6206 - 6209