1. G. A. Ivanov, A. V. Bobyl’, E. M. Ershenko, and E. I. Terukov, Tech. Phys. 59, 1482 (2014).
2. P. V. Ilyushin and Yu. N. Kucherov, Elektro, No. 5, 2 (2014).
3. T. S. Kol’tsova, F. M. Shakhov, A. A. Voznyakovskii, L. N. Lyashkov, et al., Tech. Phys. 59, 1626 (2014)
4. J. O. Bostrom, A. Campus, et al., Nauka Tekh., No. 5, 7 (2005).
5. M. E. Borisova and Yu. K. Osina, in Proceedings of XIII International Conference on Dielectric Physics, 2014 (RGPU im. A. I. Gertsena, St. Petersburg, 2014), Vol. 1, p. 42.