%0 Journal Article %A N. P. Korneichuk %A N. E. Lushpai %T Best quadrature formulas for classes of differentiable functions and piecewise-polynomial approximation %J Izvestiya. Mathematics %D 1969 %P 1335-1355 %V 3 %N 6 %I mathdoc %U http://geodesic.mathdoc.fr/item/IM2_1969_3_6_a10/ %G en %F IM2_1969_3_6_a10