Zhang, Nan; Wu, Biqi; Wissner, Allan; Powell, Dennis W.; Rabindran, Sridhar K.; Kohler, Constance; Boschelli, Frank Bioorganic and Medicinal Chemistry Letters, 2002, vol. 12, # 3 p. 423 - 425 doi: 10.1016/S0960-894X(01)00776-4