An Iterative Fractional Operational Matrix Method for Solving Fractional Undamped Duffing Equation with High Nonlinearity. European Journal of Pure and Applied Mathematics, Maryland, USA, v. 18, n. 2, p. 5884, 2025. DOI: 10.29020/nybg.ejpam.v18i2.5884. Disponível em: https://www.ejpam.com/index.php/ejpam/article/view/5884. Acesso em: 5 dec. 2025.