AliN. A., and YanchukS. V. “Rotary Motions of Autonomous Systems With Pulse Influence”. Ukrains’kyi Matematychnyi Zhurnal 49, no. 4 (April 25, 1997): 591–596. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5036.