1. V. S. Mikhalevskii, V. F. Papakin, and M. F. Sém, in: Present Problems in Science [in Russian], Izd. RGU (1967), p. 137.
2. É. K. Karabut, V. F. Keidan, V. F. Kravchenko, V. S. Mikhalevskii, V. F. Papakin, and M. F. Sém, Elektron. Tekh. Ser. 1. Élektronika SVCh, No. 9, 103 (1969).
3. D. Dyson, Nature,207, 361 (1965).