1. Yu. A. Ryzhov and V. V. Tamoikin, Izv. VUZ. Radiofiz.,13, No. 3, 356 (1970).
2. V. L. Klyatskin and V. I. Tatarskii, Izv. VUZ. Radiofiz.,15, No. 10, 1433 (1972).
3. V. I. Shishov, Izv. VUZ. Radiofiz.,11, No. 6, 866 (1968).
4. I. M. Erukhimov and V. P. Uryadov, Izv. VUZ. Radiofiz.,11, No. 12, 12, 1852 (1968).
5. V. J. Klyatskin, Zh. Eksper. i Teor. Fiz.,57, No. 9, 452 (1969).