Periodic Solutions of a Class of Duffing Differential Equations. Journal of Nonlinear Modeling and Analysis, [S. l.], v. 1, n. 2, p. 167–177, 2024. DOI: 10.12150/jnma.2019.167. Disponível em: https://gsp.tricubic.dev/jnma/article/view/13514. Acesso em: 14 mar. 2026.