1. Collection: Ionospheric Disturbances and Their Influence on Radio Communication [in Russian], Izd. Nauka, Moscow (1971).
2. H. Poeverlein, J. Atm. Terr. Phys.,28, No. 11, 1111 (1966).
3. H. Poeverlein, Phys. Rev.,136, No. 6A, 1605 (1964).
4. B. N. Gershman and G. I. Grigor'ev, Izv. Vyssh. Uchebn. Zaved., Radiofiz.,11, No. 1, 5 (1968).
5. Collection: Ionospheric Research [in Russian], Izd. Nauka, Moscow (1970), p. 86.