This text is dedicated to the memory of Israel Glazman, who was the author of many papers and books on operator theory and its applications. It opens with an essay on Glazman's life and scientific achievements, and the book then focuses on the areas of his unusually wide interests, and consists of 18 mathematical papers in spectral theory of differential operators, and linear operators in Hilbert and Banach spaces, analytic operator functions, ordinary and partial differential equations, functional equations, mathematical physics, nonlinear functional analysis, approximation theory and optimization, and mathematical statistics. This volume should be relevent to researchers working in pure and applied mathematics.