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Aref Jeribi, Spectral Theory and Applications of Linear Operators and Block Operator Matrices, 2015, 173
Monika Winklmeier, “A variational principle for block operator matrices and its application to the angular part of the Dirac operator in curved spacetime”, Journal of Differential Equations, 245, no. 8, 2008, 2145
Imen Ferjani, Aref Jeribi, Bilel Krichen, “Generalized weak demicompactness involving measure of non-strict-singularity”, Indian J Pure Appl Math, 52, no. 2, 2021, 529
Yanyan Du, Junjie Huang, “Essential spectra of upper triangular relation matrices”, Monatsh Math, 200, no. 1, 2023, 43
D. A. Zakora, “Spectral properties of operators in the problem on normal oscillations of a mixture of viscous compressible fluids”, SMFN, 69, no. 1, 2023, 73
Michael Gil’, “On location of spectra of unbounded operators in the right half-plane”, Afr. Mat., 31, no. 7-8, 2020, 1121