1. V. V. Belikovich, E. A. Benediktov, S. M. Grach, and G. I. Terina, “Double transformation of waves in scattering by artificial ionospheric irregularities,“ Abstracts of Proceedings of the XIII All-Union Conference on Propagation of Radiowaves, part 1 [in Russian], Nauka, Moscow (1981), p. 107.
2. B. Thide, H. Kopka, and P. Stubbe,Phys. Rev. Lett.,49, 1561 (1982).
3. P. Stubbe, H. Kopka, B. Thide, and H. Derblom,J. Geophys. Res.,89A, 7523 (1984).
4. T. B. Leyser, “Stimulated electromagnetic emission in the ionosphere,” Ph.D. dissertation, Uppsala Univ., Uppsala, Sweden, IRF (1989).
5. T. B. Leyser, B. Thide, H. Derblom, A. Hedberg, B. Lundborg, P. Stubbe, and H. Kopka,J. Geophys. Res.,A95, 17233 (1990).