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 December 23, 2024. https://jeelm.vgtu.lt/index.php/MMA/article/view/903.