@article{MZM_2018_103_2_a12,
     author = {S. B. Vakarchuk},
     title = {Best {Polynomial} {Approximations} and {Widths} of {Classes} of {Functions} in the {Space~}$L_2$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {307--311},
     publisher = {mathdoc},
     volume = {103},
     number = {2},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2018_103_2_a12/}
}