%0 Journal Article %A V. A. Nogin %A S. G. Samko %T On the simultaneous approximation of functions and their Riesz derivatives %J Doklady Akademii Nauk %D 1981 %P 548-550 %V 261 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/DAN_1981_261_3_a7/ %G ru %F DAN_1981_261_3_a7