LI, J.-L. On the convex null operators. Tamkang Journal of Mathematics, [S. l.], v. 33, n. 4, p. 303–308, 2002. DOI: 10.5556/j.tkjm.33.2002.278. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/278. Acesso em: 23 apr. 2024.