This book is dedicated to Sergei Mikhailovich Nikol'skii on the occasion of his eighty-fifth birthday. The collection contains new results on the following topics: approximation of functions, imbedding theory, interpolation of function spaces, convergence of series in trigonometric and general orthogonal systems, quasilinear elliptic problems, spectral theory of nonselfadjoint operators, asymptotic properties of pseudodifferential operators, and methods of approximate solution of Laplace's equation.

A collection of papers and articles honoring Sergeĭ Mihaĭlovič Nikolʹskiĭ and detailing original scientific research in the theory of functions of one and several variables and the applications to differential equations.