I. V. Protasov, “On the Suslin Number of Totally-Bounded Left-Topological Groups”, Ukr. Mat. Zhurn., vol. 54, no. 11, pp. 1581–1573, Nov. 2002, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4195