Lim, Hyun-Suk; Park, Jeong-Ju; Ko, Kwangseok; Lee, Mee-Hyun; Chung, Sung-Kee Bioorganic and Medicinal Chemistry Letters, 2004, vol. 14, # 10 p. 2499 - 2503 doi: 10.1016/j.bmcl.2004.03.001