1. Balogh, A., et al: 1995, Science 268, 1007.
2. Connell, J.J. and Simpson, J.A.: 1997, Ap. J. Lett 475, L61.
3. Connell, J.J. et al: 2000, Ap. J. in press.
4. Fisk, L.A.: 1996, J. Geophys. Res. 101, 15547.
5. Geiss, J. et al: 1994, Astron. Astrophys. 282, 924.