The Convergence of Multigrid Methods for Solving Finite Element Equations in the Presence of Singularities. Journal of Computational Mathematics, [S. l.], v. 13, n. 4, p. 315–324, 2021. Disponível em: https://global-sci.com/index.php/JCM/article/view/11186. Acesso em: 6 dec. 2025.