K. K. Elgondyev and V. G. Samoilenko, “On periodic solutions of linear differential equations with pulsed influence”, Ukr. Mat. Zhurn., vol. 49, no. 1, pp. 141–148, Jan. 1997, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/4992