Principles of Mathematical Logic by D. Hilbert and W. Ackermann 1950 Hardcover

Introduction to Hilbert Space, By Sterling K. Berberian (1961) 1st Ed. Hardcover

Theory of linear operators in Hilbert space N. I. Akhiezer, I. M. Glazman. Monog

Linear Systems and Operators in Hilbert Space Fuhrmann, Paul A.:

Hilbert by Constance Reid (Very Good HC without DJ 2nd printing of 1970 edition)

A Course in Modern Mathematical Physics Groups, Hilbert Space and Differential

Introduction to Hilbert Space, Sterling K. Berberian, 1961 HB

Linear Differential Operators. Hardcover. Cornelius Lanczos