DauylbayevM. K., and UaissovA. B. “Asymptotic Behavior of the Solutions of Boundary-value problems for Singularly Perturbed Integro-Differential Equations”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 11 (November 25, 2019): 1466-1479. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1529.