Mikhailov,B.M. et al.
Bulletin of the Academy of Sciences of the USSR, Division of Chemical Science (English Translation), 1976 , vol. 25, p. 1924 - 1927
Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 1976 , vol. 25, p. 2053 - 2056

Gmelin Handbook: B: B Comp.SVol.1/3, 10.7.1.3.2, page 55 - 59