@article{MZM_1993_53_4_a11,
     author = {O. I. Smirnov},
     title = {The {Jackson} theorem in $L_2$ for {Christenson{\textendash}Levy} systems},
     journal = {Matemati\v{c}eskie zametki},
     pages = {111--130},
     year = {1993},
     volume = {53},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1993_53_4_a11/}
}