SamoilenkoA. M., SamoilenkoV. G., and SobchukV. S. “On Periodic Solutions of the Equation of a Nonlinear Oscillator With Pulse Influence”. Ukrains’kyi Matematychnyi Zhurnal 51, no. 6 (June 25, 1999): 827–834. Accessed November 24, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/4669.