@article{MZM_1982_32_5_a13,
     author = {N. M. Miroshin and V. V. Khromov},
     title = {A problem of best approximation of functions of several variables},
     journal = {Matemati\v{c}eskie zametki},
     pages = {721--727},
     year = {1982},
     volume = {32},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1982_32_5_a13/}
}