1. W. Iraube and W. Shulze, Chem. Ber.,54, 1626 (1921).
2. I. I. Vol'nov and A. N. Shatunina, Izv. Akad. Nauk SSSR, Ser. Khim.,1966, 2031.
3. I. I. Vol'nov, V. N. Chamova, V. P. Sergeeva, and E. I. Latysheva, Zh. Neorgan. Khim.,1, 1937 (1956).
4. R. S. Johston, Analyt. Chem.,30, 511 (1958).
5. V. M. Bakulina and A. B. Tsentsiper, Izv. Akad. Nauk SSSR, Ser. Khim.,1968, No. 7.