MUMINOV, M.; RASULOV, T. Infiniteness of the Number of Eigenvalues Embedded in the Essential Spectrum of a \(2\times2\) Operator Matrix. Eurasian Mathematical Journal, [S. l.], v. 5, n. 2, p. 60–77, 2014. Disponível em: https://emj.enu.kz/index.php/main/article/view/571. Acesso em: 21 nov. 2025.