Girraj Kumar Verma, Abid Khan, Santosh Kumar Sharma,. “?-?-Contraction Mapping in Complete B-Metric Spaces”. Mathematical Statistician and Engineering Applications 70, no. 1 (January 31, 2021): 821–825. Accessed May 17, 2024. https://www.philstat.org/index.php/MSEA/article/view/2737.