Dzhemilev, U. M.; Gaisin, R. L.; Turchin, A. A.; Tolstikov, G. A. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1991 , vol. 40, # 9.2 p. 1845 - 1848 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1991 , # 9 p. 2084 - 2087