Block-Symmetric and Block-Lower-Triangular Preconditioners for PDE-Constrained Optimization Problems. Journal of Computational Mathematics, [S. l.], v. 31, n. 4, p. 370–381, 2018. DOI: 10.4208/jcm.1301-m4234. Disponível em: https://global-sci.com/index.php/JCM/article/view/12122. Acesso em: 5 dec. 2025.