HUSSIEN, A. M. Polynomial Inverse Integrating Factors, First Integral and Non-Existence of Limit Cycles in the Plane for Quadratic Systems. Science Journal of University of Zakho, [S. l.], v. 5, n. 2, p. 232–238, 2017. DOI: 10.25271/2017.5.2.374. Disponível em: https://sjuoz.uoz.edu.krd/index.php/sjuoz/article/view/502. Acesso em: 5 may. 2024.