1. Bilitza, D., Altadill, D., Truhlik, D., et al., International reference ionosphere 2016: From ionospheric climate to real-time weather predictions, Space Weather, 2017, vol. 15, pp. 418–429. https://doi.org/10.1002/2016SW001593
2. Danilkin, N.P., On the acquisition and possible use of transionograms, Geomagn. Aeron., 1974, vol. 14, no. 2, pp. 369–371.
3. Danilkin, N.P., Transionospheric radiosounding as a tool for controlling the ionospheric state, in Ionosferno–magnitnaya sluzhba (The Ionospheric and Magnetic Service), Avdyushin, S.I. and Danilov, A.D., Eds., Leningrad: Gidrometeoizdat, 1987, pp. 79–110.
4. Danilkin, N.P., Transionospheric radiosounding (review), Geomagn. Aeron. (Engl. Transl.), 2017, vol. 57, no. 5, pp. 501–511. https://doi.org/10.1134/S0016793217050048
5. Danilkin, N.P., Denisenko, P.F., Kovalev, V.A., and Sotsky, V.V., On the possibility of using the method of regularization in the problem of transionospheric sounding, Geomagn. Aeron., 1987, vol. 27, no. 4, pp. 550–552.