Vartanyan, M. M.; Karzhavina, N. P.; Karakhanov, R. A.; Mardashev, Yu. S. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1981 , vol. 30, # 4 p. 693 - 694 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1981 , # 4 p. 912 - 913