Nashine, Hemant Kumar Kumar, and Zoran Kadelburg. “Weaker Cyclic (phi,phi)-Contractive Mappings With an Application to Integro-Differential Equations”. Nonlinear Analysis: Modelling and Control 18, no. 4 (October 25, 2013): 427–443. Accessed April 26, 2025. https://www.zurnalai.vu.lt/nonlinear-analysis/article/view/13971.