1. Acharya, B.S., Rao, M.V.S., Sivaprasad, K. and Rao, Srikantha: 1979, Proc. 16th Int. Conf. Cosmic Rays, Kyoto, 8, pp. 312–317.
2. Aguirre, C., Anda, R., Trepp, A., Kakimoto, F., Mizumoto, Y., Suga, K., Inoue, N., Kawai, M., Izu, N., Kaneko, T., Yoshii, H., Nishi, K., Yamada, Y., Tajima, N., Nakatani, H., Gotoh, E., MacKeown, P.K., Murakami, K. and Toyoda, Y.: 1979, Proc. 16th Int. Conf. Cosmic Rays, Kyoto, 8, pp. 112–117.
3. Alfvén, H.: 1954, Tellus, 6, pp. 232–253.
4. Antonov, R.A. and Ivanenko, I.P.: 1975, Proc. 14th Int. Conf. Cosmic Rays, Munich, 8, pp. 2708–2713.
5. Antonov, R.A., Ivanenko, I.P. and Kuzmin, V.A.: 1979, Proc. 16th Int. Conf. Cosmic Rays, Kyoto, 9, pp. 263–268.