Title: Operator theory
Subjects: Functional analysis -- Topological algebras, normed rings and algebras, Banach algebras -- General theory of topological algebras, Ordinary differential equations -- Instructional exposition (textbooks, tutorial papers, etc.)., Textbooks, Ordinary differential equations -- Ordinary differential operators -- General spectral theory, Partial differential equations -- Spectral theory and eigenvalue problems -- General topics in linear spectral theory, Mathematical analysis, Functional analysis -- Instructional exposition (textbooks, tutorial papers, etc.)., Quantum theory -- General mathematical topics and methods in quantum theory -- Selfadjoint operator theory in quantum theory, including spectral analysis, Operator theory -- Instructional exposition (textbooks, tutorial papers, etc.)., Topological groups, Lie groups -- Locally compact abelian groups (LCA groups) -- General properties and structure of LCA groups, Harmonic analysis on Euclidean spaces -- Nontrigonometric harmonic analysis -- Orthogonal functions and polynomials, general theory, Operator theory