1. Limits to the value of the Hubble constant deduced from observations of clusters of galaxies
2. Unborn clusters
3. Freedman, W. L., Madore, B. F. & Kennicutt, R. C. 1997, in The Extragalactic Distance Scale, ed. M. Livio, M. Donahue, & N. Panagia (Cambridge: Cambridge Univ. Press), 171
4. Giovanelli, R. 1997, in The Extragalactic Distance Scale, ed. M. Livio, M. Donahue, & N. Panagia (Cambridge: Cambridge Univ. Press), 113
5. Gunn, J. E. 1978, in Observational Cosmology, ed. A. Maeder, L. Martinet, & G. Tammann (Sauverny: Geneva Obs.), 1