MALAMUD , M. M. Certain classes for expansions of the Hermitian operator with gaps. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 2, p. 215–233, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7836. Acesso em: 11 apr. 2025.