BONDAR, A. A.; DYMARSKII, Ya. M. Submanifolds of compact operators with fixed multiplicities of eigenvalues. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 9, p. 1179–1189, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2796. Acesso em: 5 dec. 2025.