1. A. A. Ionin, in Electric-Discharge CO Lasers, Ed. by M. Endo and R. F. Walter (CRC, New York, 2007), p. 201.
2. A. P. Napartovich, in Gas Lasers: Recent Developments and Future Prospects (Nato ASI Series), Ed. by W. J. Witteman and V. N. Ochkin (Luwer Academic, Dordrecht, 1995), p. 10.
3. V. A. Gurashvili, A. V. Dem’yanov, S. A. Zhdanok, et al., Inzh.-Fiz. Zh. 55, 37 (1988).
4. A. S. Golovin, V. A. Gurashvili, I. V. Kochetov, et al., Teplofiz. Vys. Temp. 24, 852 (1986).
5. E. P. Glotov, V. A. Danilychev, and N. V. Cheburkin, Tr. FIAN 142, 3 (1983).