1. H. F. Bates, Results of the HF Forward and Backscatter Program at College since 1963: Final Report, VAG R-178, College, Geophys. Inst. Univ. Alaska (1966).
2. H. G. Moller, Radio Sci.,2, No. 1, 77 (1967).
3. V. B. Smirnov (ed.), Oblique Sounding of the Ionosphere, Collection of Papers [in Russian], No. 1, Gidrometeoizdat, Leningrad (1972).
4. V. M. Driatskii, V. B. Smirnov, and I. N. Kosterin, Works of Arctic and Antarctic Scientific-Research Institute [in Russian], Vol. 351, Gidrometeoizdat, Leningrad (1978), p. 5.
5. Ch. L. Khodzha-Akhmedov and M. S. Kashurko, Works of Arctic and Antarctic Scientific-Research Institute [in Russian], Vol. 351, Gidrometeoizdat, Leningrad (1978), p. 54.