@article{MZM_1990_48_4_a5,
     author = {N. A. Il'yasov},
     title = {Approximation of periodic functions by {Fejer{\textendash}Zygmund} means in various metrics},
     journal = {Matemati\v{c}eskie zametki},
     pages = {48--57},
     year = {1990},
     volume = {48},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1990_48_4_a5/}
}