1. Sarabhai, V., Nerurkar, N. W., Duggal, S. P. and Sastry, T. S. G.Proceedings of a Symposium on Electromagnetic Phenomena in Cosmical Physics, Stockholm, 1956.
2. Sarabhai, V., Desai, U. D. and Venkatesan, D.Phys. Rev., 1955,99, 1490.
3. —Proceedings of I.U.P.A.P., Cosmic Ray Congress, Mexico, 1955.
4. Sarabhai, V. and Nerurkar, N. W.Ibid., 1955.
5. Sekido, Y., Yoshida, S. and Kamiya, Y.Rep. Ionosphere Res., Japan, 1952,6, 195.