1. Free topological groups over metrizable spaces;Arhangel’skiǐ;Topology Appl.,1989
2. Topological Groups and Related Structures;Arhangel’skiǐ,2008
3. T. Banakh, Fans and their applications in general topology, functional analysis and topological algebra, arXiv:1602.04857v2.
4. On the Ck-stable closure of the class of (separable) metrizable spaces;Banakh;Monatsh. Math.,2016
5. On μ-spaces and kR-spaces;Blasco;Proc. Amer. Math. Soc.,1977