1. V. G. Baryshevskii, Dokl. Akad. Nauk BSSR 15, 306 (1971).
2. V. G. Baryshevskii and I. D. Feranchuk, Zh. Éksp. Teor. Fiz. 61, 944 (1971) [Sov. Phys. JETP 34, 502 (1972)].
3. V. G. Baryshevskii and I. D. Feranchuk, Dokl. Akad. Nauk BSSR 18, 499 (1974).
4. G. M. Garibyan and Yan Shi, Zh. Éksp. Teor. Fiz. 61, 930 (1971) [Sov. Phys. JETP 34, 495 (1972)].
5. G. M. Garibyan and Yan Shi, Zh. Éksp. Teor. Fiz. 63, 1198 (1972) [Sov. Phys. JETP 36, 631 (1973)].