1. Normal structure in Banach spaces;Belluce;Pacific J. Math.,1968
2. On the center of a convex set;Brodskii;Dokl. Akad. Nauk SSSR,1948
3. Rotundity;Cudia,1963
4. Normed Linear Spaces;Day,1962
5. Fixed point theorems in reflexive Banach spaces;Kannan,1973