Dvornyk, A. V., and V. I. Tkachenko. “Frequency Locking of Periodic Solutions to Differential Equations With Impulsive Perturbations”. Ukrains’kyi Matematychnyi Zhurnal 74, no. 7 (August 9, 2022): 939 - 960. Accessed October 7, 2022. https://umj.imath.kiev.ua/index.php/umj/article/view/7138.