(N, ε)-pseudospectra of bounded linear operators on ultrametric Banach spaces. Gulf Journal of Mathematics, [S. l.], v. 17, n. 1, p. 12–28, 2024. DOI: 10.56947/gjom.v17i1.1665. Disponível em: https://gjom.org/index.php/gjom/article/view/1665. Acesso em: 16 sep. 2026.