CHAKIR, Y.; EL BOUCHIBTI, E. H. PRODUCT OF OPERATORS AND ∂-SPECTRUM PRESERVERS. Results in Nonlinear Analysis, [S. l.], v. 7, n. 2, p. 107–114, 2024. Disponível em: https://nonlinear-analysis.com/index.php/pub/article/view/383. Acesso em: 21 nov. 2024.