1. The power of bicompacta with first axiom of countability;Arhangel′skiĭ;Dokl. Akad. Nauk SSSR,1969
2. Foundation of General Topology in Problems and Exercises;Arkhangel′skiĭ,1974
3. On the cardinality of Urysohn spaces;Bella;Can. Math. Bull.,1988
4. On the cardinality of a topological space;Charlesworth;Proc. Am. Math. Soc.,1977
5. General Topology;Engelking,1989