Maldonado, I. C. A. Romero; Nikiforov, G. A. Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1987 , vol. 36, # 10 p. 2184 - 2185 Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1987 , # 10 p. 2356 - 2358