THAMBAN NAIR, M. Approximation of Spectral Sets and Spectral Subspaces in Banach Spaces. The Journal of the Indian Mathematical Society, [S. l.], v. 54, n. 1-4, p. 187–200, 1989. Disponível em: https://informaticsjournals.co.in/index.php/jims/article/view/21890. Acesso em: 7 nov. 2024.