Investigations on the theory of functions of several real variables and approximation of functons, Collection of articles. Dedicated to the academician S. M. Nikol'skij on the occasion of his 80th birthday, Trudy Mat. Inst. Steklov., 172, ed. S. L. Sobolev, 1985, 357 ñ. http://mi.mathnet.ru/book1165
