Khang, Nguyen Van, and Tran Dinh Son. “Influence of Non-Linear Parametric Excitation on Resonant Characteristics of Oscillating Systems”. Vietnam Journal of Mechanics 20, no. 2 (June 30, 1998): 27–36. Accessed April 26, 2025. https://vjs.ac.vn/vjmech/article/view/10018.