@article{SM_1991_69_2_a2,
     author = {B. D. Boyanov},
     title = {The optimal recovery of smooth functions},
     journal = {Sbornik. Mathematics},
     pages = {357--377},
     year = {1991},
     volume = {69},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1991_69_2_a2/}
}