Da, Hoang Van, and Nguyen Thac Sy. “Frequency Entrainment in a Self-Oscillatory System under Parametric Excitation”. Vietnam Journal of Mechanics 25, no. 3 (September 30, 2003): 137–144. Accessed March 29, 2024. https://vjs.ac.vn/index.php/vjmech/article/view/6586.