1. A. V. Bagulya, L. L. Kashkarov, N. S. Konovalova, et al., Pisma Zh. Eksp. Teor. Fiz. 97, 811 (2013) [JETP Lett. 97, 708 (2013))].
2. V. Alexeev, A. Bagulya, M. Chernyavsky, et al., Astrophys. J. 829, 120 (2016).
3. V. P. Perelygin, Sh. B. Viik, and O. Otgonsuren, Preprint No. R13-8359, OIYaI (Joint Institute for Nuclear Research, Dubna, Moscow Region, 1974).
4. S. K. Bhattacharya, J. N. Goswami, and D. Lal, J. Geophys. Res. 78, 8356 (1973).
5. A. O. Aaloe, V. D. Kolomenskii, L. K. Levskii, et al., Preprint No. R14-12937, OIYaI (Joint Institute for Nuclear Research, Dubna, Moscow Region, 1979).