1. Balthasar, H., Vazquez, M., and Wöhl, H. (1986) Astron. Astrophys. 155, 87
2. Brandenburg, A., Moss, D., Rüdiger, G., and Tuominen, I. (1990) Solar Phys. 128, 243
3. Brandenburg, A., Moss, D., and Tuominen, I. (1992) Astron. Astrophys. 265, 328
4. Canuto, V. M., Minotti, F. O., and Schilling, O. (1993) Astrophys. J. (submitted)
5. Donahue, R. A. and Baliunas, S. L. (1993) Astrophys. J. 393, L63