Bekker, R. A.; Popkova, V. Ya.
Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1990 , vol. 39, # 8.2 p. 1725 - 1728
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1990 , # 8 p. 1898 - 1901