@article{MZM_1980_27_4_a15,
     author = {K. I. Oskolkov},
     title = {Approximate properties of classes of periodic functions},
     journal = {Matemati\v{c}eskie zametki},
     pages = {651--666},
     publisher = {mathdoc},
     volume = {27},
     number = {4},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1980_27_4_a15/}
}