1. Alfv�n, H.: 1958,Tellus 10, 104.
2. Bernstein, I. B., Greene, F. M., and Kruskal, M. D.: 1957,Phys. Rev. 108, 546.
3. Block, L. P.: 1972,Cosmic Electrodynamics 3, 349.
4. Gurnett, D.: 1972, inCritical Problems of Magnetospheric Physics, Proc. Cospar/IAGA/URSI, Madrid, Spain, pp. 123?136.
5. Knorr, G. and Goertz, C. K.: 1974,Astrophys. Space Sci. 31, 209.