Karadzhov, Y.A. (1995) “Singularly perturbed linear boundary-value problems with pulse effects and the regular reduced problem”,
Ukrains’kyi Matematychnyi Zhurnal, 47(4), pp. 463–467. Available at:
https://umj.imath.kiev.ua/index.php/umj/article/view/5443 (Accessed: 10 April 2025).