New Qualitative Outcomes for Ordinary Differential Systems of Second Order. Contemporary Mathematics , [S. l.], v. 4, n. 4, p. 1210–1221, 2023. DOI: 10.37256/cm.4420233045. Disponível em: https://ojs353.mebyme.cn/index.php/CM/article/view/3045. Acesso em: 24 dec. 2025.