@article{IM2_1969_3_6_a10,
     author = {N. P. Korneichuk and N. E. Lushpai},
     title = {Best quadrature formulas for classes of differentiable functions and piecewise-polynomial approximation},
     journal = {Izvestiya. Mathematics },
     pages = {1335--1355},
     publisher = {mathdoc},
     volume = {3},
     number = {6},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1969_3_6_a10/}
}