1. Brandt, J. C.: 1968,Ann. Rev. Astron. Astrophys. 6, 267.
2. Dryer, M., Rizzi, A. W., and Shen, W.-W.: 1973,Astrophys. Space Sci. 22, 329.
3. Ershkovich, A. I.: 1976,Planet. Space Sci. 24, 287.
4. Ershkovich, A. I. and Chernikov, A. A.: 1973,Planet. Space Sci. 21, 663.
5. Ershkovich, A. I. and Nusinov, A. A.: 1970, Report at Int. Symposium on the Solar-Terr. Phys. in Leningrad, May 1970,Program and Abstracts, p. 152; also in Preprint No. 37, Space Res. Institute, Academy of Sci., Moscow.