Sengupta, Richik. “On Fixed Points of Contraction Maps Acting in \((q_1, q_2)\)-Quasimetric Spaces and Geometric Properties of These Spaces”. Eurasian Mathematical Journal 8, no. 3 (September 30, 2017): 70–76. Accessed September 18, 2025. https://emj.enu.kz/index.php/main/article/view/672.