@article{DAN_1958_120_6_a0,
     author = {D. L. Berman},
     title = {On the impossibility of constructing a linear polynomial operator furnishing an approximation within the order of the best approximation},
     journal = {Doklady Akademii Nauk},
     pages = {1175--1177},
     publisher = {mathdoc},
     volume = {120},
     number = {6},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_120_6_a0/}
}