SIRIPENSOPA, K.; NONLAOPON, K. Using Undetermined Coefficients to Solve Some Classes of Ordinary Differential Equations with Variable Coefficients. KKU Science Journal, [S. l.], v. 48, n. 4, p. 450–460, 2020. Disponível em: https://ph01.tci-thaijo.org/index.php/KKUSciJ/article/view/250197. Acesso em: 1 oct. 2026.