Gromov, S. P.; Fomina, M. V.; Alfimov, M. V. Russian Chemical Bulletin, 1993 , vol. 42, # 9 p. 1561 - 1569 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1993 , # 9 p. 1625 - 1632