1. B. V. Krylov, A. F. Radyuk, and F. I. Fedorov, Preprint No. 113 [in Russian], Institute of Physics, Academy of Sciences of the Belorussian SSR (1976).
2. I. Ya. Berson, Zh. Eksp. Teor. Fiz.,56, 1627 (1969).
3. V. G. Bagrov, P. V. Bozrikov, and D. M. Gitman, Teor. Mat. Fiz.,14, 202 (1973).
4. V. G. Bagrov, P. V. Bozrikov, and D. M. Gitman, Izv. Vyssh. Uchebn. Zaved. Fiz., No. 6, 129 (1974).
5. I. Ya. Berson, Izv. Akad. Nauk SSR, Ser. Fiz.-Tekh. N., No. 5, 3 (1969).