1. N. D. Filipp, N. Sh. Blaunshtein, L. M. Erukhimov, et al., Modern Methods for Studying Dynamic Processes in the Ionosphere [in Russian], Shtiintsa, Kishinev (1991).
2. E. L. Afraimovich, Interference Methods for Radio Sounding of the Ionosphere [in Russian], Nauka, Moscow (1982).
3. L. M. Erukhimov, A. A. Ponyatov, V. P. Uryadov, et al., Radiophys. Quantum Electron., 41, No.1, 1 (1998).
4. A. J. Stocker, N. F. Arnold, and T. B. Jones, Ann. Geophys., 18, 54 (2000).
5. D. Bilitza, in: W. R. Stone, ed., The Review of Radio Science 1999–2002, IEEE Press, New York (2002), p. 625.