Sha, Chin-Kang; Chiu, Rei-Torng; Yang, Cheng-Fen; Yao, Nai-Tung; Tseng, Wei-Hong; Liao, Fen-Ling; Wang, Sue-Lein Journal of the American Chemical Society, 1997, vol. 119, # 18 p. 4130 - 4135 doi: 10.1021/ja9643432