@article{MZM_1967_2_5_a6,
     author = {Yu. N. Subbotin},
     title = {The best approximation of a class of functions by another class},
     journal = {Matemati\v{c}eskie zametki},
     pages = {495--504},
     publisher = {mathdoc},
     volume = {2},
     number = {5},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1967_2_5_a6/}
}