1. H. Buseman, Geometry of Geodesics, Academic Press (1955).
2. N. Bourbaki, General Topology. Fundamental Structures [Russian translation], Nauka, Moscow (1968); Topological Groups. Numbers and Related Groups and Spaces, [Russian translation], Nauka, Moscow (1969).
3. Memoir. Sci. Mathem.;E. Cartan,1930
4. V. N. Berestovskii, ?Homogeneous Buseman G-spaces,? Dokl. Akad. Nauk SSSR,247, No. 3, 525?528 (1979).
5. V. A. Rokhlin and D. B. Fuchs, Beginner's Course in Topology (Geometric Chapters) [in Russian], Nauka, Moscow (1977).