Homotopy Perturbation Transform Method for solving nonlinear wave-like equation with variable coefficients. Global Journal of Science Frontier Research, [S. l.], v. 11, n. 9, p. 45–50, 2011. Disponível em: https://www.journalofscience.org/index.php/GJSFR/article/view/100122. Acesso em: 6 feb. 2026.