ABDULAZEEZ, S. T. .; HUSSEIN , A. M. . The Existence of a Polynomial Inverse Integrating Factors and Studies About the Limit Cycles for Cubic, Quartic and Quintic Polynomial Systems. Baghdad Science Journal, Iraq, Baghdad, v. 18, n. 2, p. 0322, 2021. DOI: 10.21123/bsj.2021.18.2.0322. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/3623. Acesso em: 31 jul. 2021.