1. D. Marcuse, Bell Syst. Techn. J.,41, 1557 (1962);42, 415 (1963).
2. S. Rand, Phys. Rev.,136, B231 (1964).
3. V. F. Bunkin and M. V. Fedorov, Zh. Éksperim. i Teor. Fiz.,49, 1215 (1965).
4. M. M. Denisov and M. V. Fedorov,Zh. Éksperim. i Teor. Fiz.,53,1340 (1967).
5. S. M. Rytov, Introduction to Statistical Radio Physics [in Russian], Izd. Nauka, Moscow (1966).