Khairullin,V.K.; Eliseenkov,V.N. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation)Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 19671967, # 1 p. 87 - 9194 - 99 doi: 10.1007/BF00907104