Starting with a definition of Hilbert space and its geometry, this text explores the general theory of bounded linear operators, the spectral analysis of compact linear operators, and unbounded self-adjoint operators. Familiarity with analysis and analytic geometry is the only prerequisite. Extensive appendixes complement the text. 1969 edition. Reprint of the John Wiley & Sons, Inc., New York, 1969 edition.
Theory of Linear Operators in Hilbert Space by N. I. Akhiezer, I. M. Glazman This classic textbook introduces linear operators in Hilbert Space, and presents the geometry of Hilbert space and the spectral theory of unitary and self-adjoint operators. Invaluable for every mathematician and physicist. 1961, 1963 edition.
Applied Functional Analysis by D.H. Griffel This introductory text examines applications of functional analysis to mechanics, fluid mechanics, diffusive growth, and approximation. Covers distribution theory, Banach spaces, Hilbert space, spectral theory, Frechet calculus, Sobolev spaces, more. 1985 edition.