Saha, Apu Kumar, and Debasish Bhattacharya. “Countable Fuzzy Topological Space and Countable Fuzzy Topological Vector Space”. Journal of Mathematical and Fundamental Sciences 47, no. 2 (June 1, 2015): 154-166. Accessed October 20, 2025. https://journals.itb.ac.id/index.php/jmfs/article/view/533.