Nonlinear Ritz Approximation for the Camassa-Holm Equation by Using the Modify Lyapunov-Schmidt method . Baghdad Science Journal, Iraq, Baghdad, v. 20, n. 5, p. 1731, 2023. DOI: 10.21123/bsj.2023.6932. Disponível em: https://bsj.uobaghdad.edu.iq/index.php/BSJ/article/view/6932.. Acesso em: 3 jan. 2025.