Perestyuk, N. A., and A. M. Samoilenko. “On the Existence of Periodic Solutions for Certain Classes of Systems of Differential Equations With Random Pulse Influence”. Ukrains’kyi Matematychnyi Zhurnal 53, no. 8 (August 25, 2001): 1061-1079. Accessed May 25, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4327.