Strіlets O. Reduction of the Gram operator for some classes of the systems of subspaces. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 76, n. 5, p. 765–775, 2024. DOI: 10.3842/umzh.v76i5.7915. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7915. Acesso em: 5 dec. 2025.