On spectrum and approximations of one class of sign-symmetric matrices
On spectrum of a periodic operator with a small localized perturbation
On Symmetries in the Theory of Finite Rank Singular Perturbations
On Temple--Kato like inequalities and applications
On the absolutely continuous spectrum in a model of irreversible quantum graph
On the Absolutely Continuous Spectrum of Sturm-Liouville Operators with Applications to Radial Quantum Trees
On the absolutely continuous spectrum of the Laplace-Beltrami operator acting on p-forms for a class of warped product metrics
On the Accurate Finite Element Solution of a Class of Fourth Order Eigenvalue Problems
On the approximate normality of eigenfunctions of the Laplacian
On the Approximation of Isolated Eigenvalues of Ordinary Differential Operators
On the basis property of the root function systems of regular boundary value problems for the Sturm-Liouville operator
On the Basis Property of the Root Functions of Differential Operators with Matrix Coefficients
On the Bethe-Sommerfeld conjecture for periodic Maxwell operators
On the boundary of the pseudospectrum and its fault points
On the Chebyshev properties of system of eigenfunctions for Sturm--Liouville problem with singular coefficients
On the comparison of the Dirichlet and Neumann counting functions
On the completeness of generalized eigenfunctions of elliptic cone operators
On the completeness of the system of root vectors for first-order systems
On the concentration-compactness phenomenon for the first Schrodinger eigenvalue
On the Construction of Isospectral Vectorial Sturm-Liouville Differential Equations