Titova, K. V.; Kolmakova, E. I.; Rosolovskii, V. Ya. Russian Journal of Inorganic Chemistry (Translation of Zhurnal Neorganicheskoi Khimii), 1978 , vol. 23, p. 634 - 636 Zhurnal Neorganicheskoi Khimii, 1978 , vol. 23, p. 1146 - 1149