1. A. G. Kislyakov, Yu. V. Lebsky, and A. I. Naumov,Izv. Vyssh. Uchebn. Zaved. Radiofiz,9, 1791 (1968).
2. I. L. Bershtein, and V. L. Sibiryakov,Radiotekh. Élektron,3, 290 (1958).
3. J. Zmuidzinas, in: Proc. 30th ESLAB Symp. “Submillimeter and Far-Infrared Space Instrumentation,” The Netherlands, ESA SP-388 (1996), p. 151.
4. H. Van de Stadt, J. Mees, Z. Barber, M. Blamire, P. Dieleman, and T. De Graauw,Int. J. IR & MM Waves,19, 91 (1996).
5. E. M. Gershenzon, M. E. Gershenzon, G. N. Gol'tsman, A. D. Semenov, and S. V. Sergeev,Pis'ma. Zh. Éksp. Tekh. Fiz.,34, 281 (1981).