ShvetsA. Yu. “Deterministic Chaos of a Spherical Pendulum under Limited Excitation”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 4 (April 25, 2007): 534–548. Accessed November 25, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3327.