Burilov, A. R.; Drozdova, Ya. A.; Pudovik, M. A.; Pudovik, A. N. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1991 , vol. 40, # 9.2 p. 1885 - 1890 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1991 , # 9 p. 2127 - 2132