On approximation and error estimate  for  Poisson equation in Banach space. Letters on Applied and Pure Mathematics, [S. l.], v. 2, n. 1, p. 35–41, 2024. Disponível em: https://lapmjournal.com/index.php/lapm/article/view/v2n1a27. Acesso em: 4 jul. 2025.