Atakhan, N., K.S. Nurpeissov, and K.T. Konisbayeva. “Asymptotic Estimations of the Solution for a Singularly Perturbed Equation With Unbounded Boundary Conditions”. Bulletin of the Karaganda University. Mathematics Series 108, no. 4 (December 30, 2022): 20–33. Accessed July 2, 2025. https://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/521.