VDOVENKO, T.; DUDKIN, M. E. On nonsymmetric rank one singular perturbations of selfadjoint operators. Methods of Functional Analysis and Topology, [S. l.], v. 22, n. 2, p. 137–151, 2016. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/632. Acesso em: 18 dec. 2025.