@article{MZM_2009_86_3_a1,
     author = {S. B. Vakarchuk and V. I. Zabutnaya},
     title = {A {Sharp} {Inequality} of {Jackson--Stechkin} type in~$L_2$ and the {Widths} of {Functional} {Classes}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {328--336},
     publisher = {mathdoc},
     volume = {86},
     number = {3},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2009_86_3_a1/}
}