Yew, Kyoung Han; Koh, Han Joong; Lee, Hai Whang; Lee, Ikchoon
Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999), 1995 , # 12 p. 2263 - 2268

Gupte; Shivarkar; Chaudhari
Chemical Communications, 2001 , # 24 p. 2620 - 2621

American Cyanamid Company
Patent: US4623662 A1, 1986 ;