KaradzhovYu. A. “Singularly Perturbed Linear Boundary-Value Problems With Pulse Effects and the Regular Reduced Problem”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 4 (April 25, 1995): 463–467. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5443.