Poletskikh, V. M., and S. S. Shestakov. “On Topological Groups With Weak Minimality (maximality) Condition for Noncompact Subgroups”. Ukrains’kyi Matematychnyi Zhurnal, vol. 46, no. 10, Oct. 1994, pp. 1393–1398, https://umj.imath.kiev.ua/index.php/umj/article/view/5619.