HUA, Mao; SANYANG, Liu. Posets and Closure Operators Relative to Matroids. MATEMATIKA, [S. l.], v. 28, p. 77–85, 2012. DOI: 10.11113/matematika.v28.n.317. Disponível em: https://matematika.utm.my/index.php/matematika/article/view/317. Acesso em: 22 jul. 2024.