Sinyashin, O. G.; Karimullin, Sh. A.; Batyeva, E. S.; Pudovik, A. N. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1982 , vol. 31, # 7 p. 1491 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1982 , # 7 p. 1671 - 1672