1. Goldstein, R. M., Science, 144, 598 (1969).
2. Pecker, J.-C., Roberts, A. P., and Vigier, J.-P., Nature, 237, 227 (1972).
3. Pecker, J.-C., Tait, W., and Vigier, J.-P., Nature, 241, 338 (1973).
4. Gordon, I. M., Astrophys. Lett., 2, 49 (1968).
5. Aubier-Giraud, M., Boichot, A., Leblanc, Y., and Steinberg, J. L., Astr. Astrophys., 10, 362 (1971).