Prajisha, E., and P. Shaini. “Coupled Coincidence Point Theorems of Mappings in Partially Ordered Metric Spaces”. *Journal of Nonlinear Analysis and Optimization: Theory & Applications* 11, no. 1 (March 28, 2020): 29-40. Accessed December 9, 2021. http://www.math.sci.nu.ac.th/ojs302/index.php/jnao/article/view/529.