Belen'kii,G.G. et al.
Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1976 , vol. 25, # 10 p. 2208 - 2210
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1976 , vol. 25, # 10 p. 2365 - 2366