1. T. G. Zagurenko, V. M. Kornilov, and A. N. Lachinov, Zh. Tekh. Fiz. 71(8), 27 (2001) [Tech. Phys. 46, 956 (2001)].
2. A. N. Lachinov and N. V. Vorob’eva, Usp. Fiz. Nauk 176, 1249 (2006) [Phys. Usp. 49, 1223 (2006)].
3. L. N. Dobretsov and M. V. Gomoyunova, Emission Electronics (Nauka, Moscow, 1966; Israel Program for Scientific Translations, Jerusalem, 1971).
4. B. B. Alchagirov, Kh. Kh. Kalazhokov, and Kh. B. Khokonov, Izv. Akad. Nauk SSSR, Ser. Fiz. 55, 2463 (1991).
5. Kh. I. Ibragimov and V. A. Korol’kov, Inorg. Mater. 37, 567 (2001).