@article{MZM_1987_41_1_a4,
     author = {V. A. Yudin},
     title = {Jackson's theorems in $L_2$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {43--47},
     publisher = {mathdoc},
     volume = {41},
     number = {1},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1987_41_1_a4/}
}