1. N. I. Zaitsev, T. B. Pankratova, M. I. Petelin, et al., Radiotekh. Élektron. (Moscow) 19, 1056 (1974).
2. A. G. Luchinin, O. V. Malygin, G. S. Nusinovich, and V. A. Flyagin, Zh. Tekh. Fiz. 53, 1629 (1983) [Sov. Phys. Tech. Phys. 28, 1001 (1983)].
3. S. Spira-Hakkarainen, K. E. Kreischer, and R. J. Temkin, IEEE Trans. Plasma Sci. 18, 334 (1990).
4. M. K. Hornstein, V. S. Bajaj, R. G. Griffin, et al., in Proceedings of the Joint 29th International Conference on Infrared and Millimeter Waves and the 12th International Conference on Terahertz Electronics, Karlsruhe (Germany), 2004, pp. 147–148.
5. T. Idehara et al., IEEE Trans. Plasma Sci. 27, 340 (1999).