Mirzakulova, A. E., and M. K. Dauylbayev. “Asymptotic Estimates of Solutions Boundary Value Problem for Singularly Perturbed Integro-Differential Equations”. Journal of Mathematics, Mechanics and Computer Science 76, no. 1 (March 23, 2013): 35–42. Accessed January 3, 2025. https://bm.kaznu.kz/index.php/kaznu/article/view/85.