%0 Journal Article %A S. A. Telyakovskii %T Approximation of differentiable functions by de la Vallée Poussin's sums %J Doklady Akademii Nauk %D 1958 %P 426-429 %V 121 %N 3 %U http://geodesic.mathdoc.fr/item/DAN_1958_121_3_a7/ %G ru %F DAN_1958_121_3_a7