“On the Unique Solvability of a Nonlinear Nonlocal Boundary-Value Problem for Systems of Second Order Functional Differential Equations”. Neliniini Kolyvannya 19, no. 2 (June 29, 2016): 203–216. Accessed April 12, 2026. https://nosc.imath.kiev.ua/index.php/nosc/article/view/823.