1. Bucciarelli, B, Lattanzi, L. G., and Taff, L. G. 1993, Astrophys.J., 103, 1689
2. Lasker, B. M., et al. 1990 Astron.J., 99, 2019
3. Morrison, J. E., et al. 1996a, Astron.J., 111, 1405
4. Morrison, J. E., Smart, R. L., Taff, L. G., 1996b, submitted to Mon.Not.R.astron.Soc.
5. Röser, S., Bastian, U., and Kuzmin, A. V. 1995, I.A.U. Colloquium 148, Astron.Soc. Pacific Conference Series, Vol 84, ed. J. M. Chapman et al.