@article{DAN_1970_190_2_a4,
     author = {N. P. Korneichuk},
     title = {Upper bounds of best approximations on classes of differentiable periodic functions in the metrics~$C$ and $L$},
     journal = {Doklady Akademii Nauk},
     pages = {269--271},
     publisher = {mathdoc},
     volume = {190},
     number = {2},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_190_2_a4/}
}