Dzhemilev, U. M.; Dokichev, V. A.; Safuanova, R. M.; Tolstikov, G. A. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1990 , vol. 39, # 2.2 p. 430 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1990 , # 2 p. 492 - 493