@article{ZVMMF_1978_18_6_a22,
     author = {N. M. Andrushevskii and N. P. Zhidkov and B. M. Shchedrin},
     title = {The optimal approximations of functions by a finite number of their fourier coefficients},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {1595--1599},
     publisher = {mathdoc},
     volume = {18},
     number = {6},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1978_18_6_a22/}
}