Babu, G., and K. Kidane. “COMMON FIXED POINT THEOREMS FOR TWO PAIRS OF SELFMAPS SATISFYING GENERALIZED WEAK CONTRACTIVE CONDITION”. Journal of Nonlinear Analysis and Optimization: Theory & Applications (JNAO), vol. 4, no. 1, May 2013, pp. 13-28, https://ph03.tci-thaijo.org/index.php/jnao/article/view/2681.