Kalugin, V. E.; Litvinov, V. P. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1991 , vol. 40, # 7 p. 1391 - 1394 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1991 , # 7 p. 1574 - 1578