@article{MZM_2011_90_5_a10,
     author = {M. Sh. Shabozov and G. A. Yusupov},
     title = {Best {Polynomial} {Approximations} in~$L_2$ of {Classes} of $2\pi${-Periodic} {Functions} and {Exact} {Values} of {Their} {Widths}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {764--775},
     publisher = {mathdoc},
     volume = {90},
     number = {5},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2011_90_5_a10/}
}