Fabrichnyi,B.P. et al.
Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1976 , vol. 25, p. 2359 - 2361
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1976 , vol. 25, # 11 p. 2534 - 2536