V. I. Arnautov and E. G. . Zelenyuk, “Problem of completeness of maximal topological groups”, Ukr. Mat. Zhurn., vol. 43, no. 1, pp. 21–27, Jan. 1991, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/9300