Zav'yalov,S.I. et al.
Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1976 , vol. 25, p. 1353 - 1356
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1976 , vol. 25, p. 1411 - 1413