1. Alexander, D., and Acton, L. W.: 2001, The Active Sun, in The Century of Space Science, Chapter 46, Kluwer, Netherlands.
2. Bigelow, F. H.: 1890, Further Study of the Solar Corona. New Haven.
3. Bryant, D. A., Cline, T. L., Desai, U. D., and McDonald, F. B.: 1962, J. Geophys. Res. 67, 4983.
4. Burlaga, L. F.: 1991, in: Schwenn, R. and Marsch, E. (eds.), Physics of the Inner Heliosphere 2, Springer-Verlag, Berlin and Heidelberg, p. 1.
5. Cane, H. V., Reames, D. V., and von Rosenvinge, T. T.: 1988, J. Geophys. Res. 93, 9555.