GIL', M. On similarity of unbounded perturbations of selfadjoint operators. Methods of Functional Analysis and Topology, [S. l.], v. 24, n. 1, p. 27–33, 2018. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/681. Acesso em: 15 dec. 2025.