1. An extension of Banach's contraction principle;Edelstein,1961
2. On fixed and periodic points under contractive mappings;Edelstein;J. London Math. Soc.,1962
3. A note on contractive mappings;Rakotch,1962
4. Fixpoint theorem for contractions of a well-chained topological space;Davis,1963
5. Topologie Générale;Bourbaki,1949