Watanabe, Toshihiro; Kinoyama, Isao; Kakefuda, Akio; Okazaki, Toshio; Takizawa, Kenji; Hirano, Seiko; Shibata, Hiroshi; Yanagisawa, Isao Chemical and Pharmaceutical Bulletin, 1997 , vol. 45, # 6 p. 996 - 1007