@article{DAN_1973_213_3_a6,
     author = {N. P. Korneichuk},
     title = {On uniform approximation of periodic functions by subspaces of finite dimension},
     journal = {Doklady Akademii Nauk},
     pages = {525--528},
     year = {1973},
     volume = {213},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_213_3_a6/}
}