1. G. V. Sholin, Dokl. Akad. Nauk SSSR, Ser. Fiz.,195, No. 3, 589 (1970).
2. E. A. Oks, Dokl. Akad. Nauk SSSR, Ser. Fiz.,275, No. 3, 607 (1984).
3. A. I. Zhuzhunashvili and E. A. Oks, Zh. Eksp. Teor. Fiz.,73, No. 6(12), 2142 (1977).
4. V. P. Gavrilenko and E. A. Oks, Zh. Eksp. Teor. Fiz.,80, No. 6, 2150 (1981).
5. E. A. Oks and Yu. M. Shagiev, Preprint No. 76, Institute of Applied Physics of the Academy of Sciences, Gor'kii (1983).