@article{MZM_1986_39_3_a7,
     author = {N. A. Il'yasov},
     title = {Approximation of periodic functions by {Zygmund} means},
     journal = {Matemati\v{c}eskie zametki},
     pages = {367--382},
     publisher = {mathdoc},
     volume = {39},
     number = {3},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1986_39_3_a7/}
}