Cherstkov, V. F.; Galakhov, M. V.; Mysov, E. I.; Sterlin, S. R.; German, L. S. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1989 , vol. 38, # 6.2 p. 1219 - 1223 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1989 , # 6 p. 1336 - 1340