NguyenVan Dao, NguyenVan Dinh, and TranKim Chi. “Van Der Pol Oscillator under Parametric and Forced Excitations”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 2 (February 25, 2007): 206–216. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3304.