Alinejad, Z., and K. Mirmostafaee. “GENERALIZED CONTRACTIVE MAPPINGS IN b-METRIC SPACES”. Journal of Nonlinear Analysis and Optimization: Theory & Applications (JNAO), vol. 9, no. 1, Mar. 2018, pp. 39-48, https://ph03.tci-thaijo.org/index.php/jnao/article/view/2869.