La Rosa, Vincenzo, and Pasquale Vetro. “Common Fixed Points for Alpha-Psi-Phi-Contractions in Generalized Metric Spaces”. Nonlinear Analysis: Modelling and Control 19, no. 1 (January 20, 2014): 43–54. Accessed May 5, 2024. https://www.journals.vu.lt/nonlinear-analysis/article/view/13691.