Ellaggoune, Selma, and Khaireddine Fernane. “On the Number of Limit Cycles in a Liénard-Like Perturbation of a Non-Linear Quadratic Isochronous Center”. Discontinuity, Nonlinearity, and Complexity 14, no. 1 (March 1, 2025): 133–143. Accessed October 17, 2026. https://lhscientificpublishing.com/index.php/DNC/article/view/1502.