Theory and applications of differentiable functions of several variables, 15 : dedicated to academician Sergeĭ Mikhaĭlovich Nikolʹskiĭ on his eighty-fifth birthday : collection of papers - Matematicheskiĭ institut im. V.A. Steklova; Kudri︠a︡vt︠s︡ev, L. D.; Nikolʹskiĭ, Sergeĭ Mikhaĭlovich (Proceedings of the Steklov Institute of Mathematics, 1994)