1. A. B. Blagoev, Yu. M. Kagan, et al., Zh. Tekh. Fiz.,44, 333 (1974).
2. A. B. Blagoev, N. B. Kolokolov, et al., Zh. Tekh. Fiz.,47, 2102 (1977).
3. V. I. Demidov and N. B. Kolokolov, Zh. Tekh. Fiz.,50, 564 (1980).
4. V. I. Demidov and N. B. Kolokolov, Phys. Lett.,89A, 397 (1982).
5. V. I. Demidov and N. B. Kolokolov, in: Metastable States of Atoms and Molecules and Methods of their Investigation [in Russian], Izd. Chuvash Gos. Univ., Cheboksary (1979), No. 2, p. 41.