Hu, Huan, Jianhe Shen, Zheyan Zhou, and Zhonghui Ou. “Relaxation Oscillations in Singularly Perturbed Generalized Lienard Systems With Non-Generic Turning Points”. Mathematical Modelling and Analysis 22, no. 3 (May 19, 2017): 389-407. Accessed November 22, 2024. https://jest.vgtu.lt/index.php/MMA/article/view/903.