Potapov, G. P.; Punegov, V. V.; Dzhemilev, U. M. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1985 , vol. 34, # 7 p. 1342 - 1345 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1985 , # 7 p. 1468 - 1471