1. Topological Groups and Related Structures;Arhangel'skii,2008
2. Algebra;Bourbaki,1989
3. General Topology;Engelking,1989
4. Absolute Retracts and Infinite Dimensional Manifolds;Fedorchuk,1992
5. Flabby maps, multivalued retractions and functors;Fedorchuk;Usp. Mat. Nauk,1986