1. Imshennik, V. S. and Syrovatskii, S. I.: 1967, JETP 25, 656.
2. Petschek, H. E.: 1964, in W. N. Hess (ed.), AAS-NASA Symposium on Physics of Solar Flares, p. 425.
3. Smith, D. F. and Priest, E. R.: 1972, Astrophys. J. 176, 487.
4. Syrovatskii, S. I.: 1966a, Soviet Astron. AJ 10, 270.
5. Syrovatskii, S. I.: 1966b, JETP 23, 754.