1. Yu. M. Bukker, A. S. Valeev, A. A. Vanin, et al., USSR Invetror’s Certificate No. 659642, Byull. Izobret., No. 16 (1979).
2. V. M. Kuznetsov, Vacuum Technology (VINITI, Moscow, 1977), No. 8.
3. B. A. Chenov, S. P. Oles’kiv, and B. S. Oles’kiv, Fiz. Élektron. (Lvov) 38, 66 (1989).
4. G. F. Dolidze, D. V. Yakashvili, V. N. Vigdorovich, and G. A. Ukhlinov, USSR Invetror’s Certificate No. 544711, Byull. Izobret., No. 4 (1977).
5. B. N. Gritsyuk and V. N. Strebezhev, Prib. Tekh. Éksp., No. 5, 157 (1997).