1. M. L. Ter-Mikaelyan, The Influence of the Medium on High-Energy Electromagnetic Processes (AN ArmSSR, Yerevan, 1969) [in Russian].
2. M. L. Ter-Mikaelyan, Sov. Phys. Dokl. 5, 1015 (1960).
3. F. R. Artutyunyan, K. A. Isparyan, and A. G. Oganesyan, Sov. J. Nucl. Phys. 1, 604 (1965).
4. F. R. Artutyunyan and M. L. Ter-Mikaelyan, Usp. Fiz. Nauk 107, 332 (1972).
5. V. L. Ginzburg and V. N. Tsytovich, Phys. Rep. 49, 1 (1979).