Sintunavarat, W. and Kumam, P. (2013) “PPF DEPENDENT FIXED POINT THEOREMS FOR RATIONAL TYPE CONTRACTION MAPPINGS IN BANACH SPACES”, Journal of Nonlinear Analysis and Optimization: Theory & Applications (JNAO), 4(2), pp. 157–162. available at: https://ph03.tci-thaijo.org/index.php/jnao/article/view/2712 (accessed: 2 September 2026).