1. Bessel, M.S. and Norris, J. 1984, Ap. J., 285, 622.
2. Binggeli, B., Sandage, A. and Tammann, G. A. 1985, Ap. J., 89, 66.
3. Binggeli, B., Tarenghi, M. and Sandage, A. 1989, Astr. Ap., (in press).
4. Carr, B. J. 1989, in The Epoch of Galaxy Formation, ed. C. S. Frenk et al., (Dordrecht: Kluwer Academic), 227.
5. Dearborn, D., et al., 1986, Ap. J., 300, 314.