1. Aizu, H., Fujimoto, Y., Hasegawa, S., Koshiba, M., Mito, I., Nishimura, J., Yokoi, K., and Schein, M.: 1961,Phys. Rev. 121, 1206.
2. Anand, K. C., Biswas, S., Lavakare, P. J., Ramadurai, S., Sreenivasan, N., Bhatia, V. S., Chohan, V. S., and Pabbi, S. D.: 1966,J. Geophys. Res. 71, 4687.
3. Balasubrahmanyan, V. K., Hagge, D. E., Ludwig, G. H., and McDonald, F. B.: 1966,J. Geophys. Res. 71, 1771.
4. Bhatia, V. S., Biswas, S., and Ramadurai, S.: 1969a, T.I.F.R. Preprint No. NE 69-3, Bombay.
5. Bhatia, V. S., Biswas, S., Chohan, V. S., Kainth, P. S., and Pabbi, S. D.: 1969b, T.I.F.R. Preprint No. NE 69-14.