1. R.H. Bing, Metrization of topological spaces. Canad. J. Math. 3, 175–186 (1951)
2. R. Engelking, General Topology (Heldermann Verlag, Berlin, 1989)
3. R. Engelking, Theory of Dimensions, Finite and Infinite (Heldermann Verlag, Lemgo, 1995)
4. H.J. Kowalsky, Einbettung metrischer Räume. Arch. Math. 8, 336–339 (1957)
5. S. Lefschetz, Algebraic Topology (American Mathematical Society, New York, 1942)