Pelyukh, G. P. “On the Existence of Local Smooth Solutions of Systems of Nonlinear Functional Equations With Deviations Dependent on Unknown Functions”. Ukrains’kyi Matematychnyi Zhurnal 53, no. 1 (January 25, 2001): 64–77. Accessed December 5, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/4222.