1. B. I. Moskalev, A Discharge in a Hollow Cathode [in Russian], Izd. Énergiya, Moscow (1969).
2. V. B. Tyutyunnik and V. M. Tkachenko, Radiotekhnika i Élektronika,17, 1101 (1972).
3. N. N. Gorobets, A. F. Lyakhovskii, V. M. Tkachenko, and V. B. Tyutyunnik, Radiotekhnika, No. 18 [in Russian], Izd. KhGU, Khar'kov (1971).
4. V. M. Tkachenko and V. B. Tyutyunnik, Transactions of Conferences on Electronics Engineering, No. 2 (18) [in Russian], (1970), p. 91.
5. V. M. Tkachenko and V. B. Tyutyunnik, Zh. Tekh. Fiz.,42, 67 (1972).