@article{SM_1968_5_3_a1,
     author = {V. A. Baskakov},
     title = {The order of approximation of differentiable functions by certain positive linear operators},
     journal = {Sbornik. Mathematics},
     pages = {333--350},
     publisher = {mathdoc},
     volume = {5},
     number = {3},
     year = {1968},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1968_5_3_a1/}
}