1. Aprodov, V.A., Zony zemletryasenii (Earthquake Zones), Moscow: Mysl’, 2000.
2. Astafyeva, E.I. and Heki, K, Vertical TEC over seismically active region during low solar activity, J. Atmos. Sol.- Terr. Phys., 2011, vol. 73, no. 13, pp. 1643–1652. doi 10.1016/j.jastp.2011.02.020
3. Chavdarov, S.S., Chasovitin, Yu.K., Chernysheva, S.P., and Sheftel’, V.M., Sredneshirotnyi sporadicheskii sloi E ionosfery (Midlatitude Sporadic E Layer of the Ionosphere), Moscow: Nauka, 1975.
4. Chen, Y.-I., Liu, J.-Y., Tsai, Y.-B., and Chen, C.-S, Statistical tests for pre-earthquake ionospheric anomaly, Terr. Atmos. Ocean. Sci. J., 2004, vol. 15, no. 3, pp. 385–396.
5. Elektromagnitnye predvestniki zemletryasenii (Electromagnetic Earthquake Precursors), Sadovskii, M.A., Ed., Moscow: Nauka, 1982.