1. Baade, W. (1951), Pub. Obs. Univ. Michigan 10, 7.
2. Brocato, E., Buonanno, R., Castellani, V., Walker, A.R. (1989), Astrophys. J. Suppl. 71, 25.
3. Caldwell, J.A.R., Coulson, I.M. (1986), M.N.R.A.S. 218, 223.
4. Caldwell, J.A.R., Laney, C.D. (1990), these proceedings.
5. Chiosi, C., Bertelli, G., Meylan, G., Ortolani, S. (1989), Ast. Astrophys. 219, 167.