RASULOV, T. H.; DILMURODOV, E. B. Eigenvalues and virtual levels of a family of 2×2 operator matrices. Methods of Functional Analysis and Topology, [S. l.], v. 25, n. 3, p. 273–281, 2019. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/731. Acesso em: 13 dec. 2025.