Continuity of the spectrum and Weyl type theorems for extension of 2-isometric operators. Gulf Journal of Mathematics, [S. l.], v. 10, n. 2, p. 1–8, 2021. DOI: 10.56947/gjom.v10i2.503. Disponível em: https://gjom.org/index.php/gjom/article/view/503. Acesso em: 21 sep. 2026.