1. Alexandrov, P., Urysohn, P., Sur les espaces topologiques compacts, Bull. Acad. Pol. (A) (1923), 5–8.
2. Alexandrov, P., Urysohn, P., Zur Theorie der topologischen Räume, Math. Ann.
92 (1924), 258–266.
3. Alexandrov, P., Urysohn, P., Memoire sur les espaces topologiques compacts, Verh. Kon. Akad. Amster-
dam
14 (1929), 1–93.
4. Birkhoff, G., A new definition of limit, Bull. Amer. Math. Soc.
41 (1935), 635.
5. Birkhoff, G., Moore-Smith convergence in general topology, Ann. Math.
38 (1937), 39–56.