Perestyuk, N. A., & Samoilenko, A. M. (2001). On the Existence of Periodic Solutions for Certain Classes of Systems of Differential Equations with Random Pulse Influence. Ukrains’kyi Matematychnyi Zhurnal, 53(8), 1061-1079. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/4327