Panasyuk, S.P., and S.R. Sultanov. 1992. “On the Problem of the Dieudonne Completeness of the Spaces of Closed Subspaces and Subgroups ”. Ukrains’kyi Matematychnyi Zhurnal 44 (11): 1525-29. https://umj.imath.kiev.ua/index.php/umj/article/view/8255.