Zhelinski, Vasil, and Boyan Zlatanov. “On the UC and UC$^*$ Properties and the Existence of Best Proximity Points in Metric Spaces”. Ann. Sofia Univ. Fac. Math. and Inf. 109 (December 12, 2022): 121–146. Accessed November 16, 2024. https://annual.uni-sofia.bg/index.php/fmi/article/view/556.