TEJUMOLA, H. O. . Integral Conditions Of Existence And Non-Existence Of Periodic Solutions Of Some Sixth And Fifth Order Ordinary Differential Equations. Journal of the Nigerian Mathematical Society, [S. l.], v. 31, n. 1-3, p. 23–33, 2021. Disponível em: https://ojs.ictp.it/jnms/index.php/jnms/article/view/744. Acesso em: 20 apr. 2024.