1. N. G. Rambidi, N. F. Stepanov, A. I. Dement'ev, and V. V. Ugarov, in: Bonds and Molecular Structure [in Russian], Nauka, Moscow (1984), pp. 5?20.
2. R. Z. Deyanov, K. P. Petrov, V. V. Ugarov, et al., Zh. Strukt. Khim.,26, No. 5, 58 (1985).
3. U. Gesenhues and H. Wendt, Z. Phys. Chemie,132, 121 (1982).
4. A. I. Morozov and I. S. Morozov, Zh. Neorg. Khim.,18, No. 4, 989 (1973).
5. V. B. Nesterenko, A. V. Zinov'ev, and M. A. Bazhin, Vestnik Akad. Nauk BSSR, Ser. Fiz.-Tekhnol. Nauk, No. 2, 32 (1967).