On Block Preconditioners for PDE-Constrained Optimization Problems. Journal of Computational Mathematics, [S. l.], v. 32, n. 3, p. 272–283, 2018. DOI: 10.4208/jcm.1401-CR4. Disponível em: https://global-sci.com/index.php/JCM/article/view/12156. Acesso em: 5 dec. 2025.