1. S. Agmon, A. Douglis, and L. Nirenberg, Estimates near the Boundary for Solutions of Elliptic Partial Differential Equations Satisfying General Boundary Conditions. I [Russian translation], Inostrannaya Literatura, Moscow (1962).
2. P. S. Aleksandrov, Introduction to Set Theory and General Topology [in Russian], Nauka, Moscow (1977).
3. P. A. Aleksandrjan and È. A. Mirzahanjan, General Topology [in Russian], Vyssh. Shkola, Moscow (1979).
4. D. Arlt, “Zusammenziehbarkeit der allgemeinen linearen Gruppe des Raumes c 0 der Nullfolgen,” Invent. Math., 1, 36–44 (1966).
5. D. V. Beklemishev, Supplementary Chapters in Linear Algebra [in Russian], Nauka, Moscow (1983).