Choban, Mitrofan, and Ekaterina Mihaylova. “Submetrizable Spaces and Open Mappings”. Acta et Commentationes Exact and Natural Sciences 10, no. 2 (January 12, 2021): 32-46. Accessed September 28, 2021. https://revista.ust.md/index.php/acta_exacte/article/view/593.