ElgondyevK. K., and SamoilenkoV. G. “On Periodic Solutions of Linear Differential Equations With Pulsed Influence”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 1 (January 25, 1997): 141–148. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4992.