@article{SM_1970_10_1_a7,
     author = {P. L. Ul'yanov},
     title = {Imbedding theorems and relations between best approximations (moduli of continuity) in different metrics},
     journal = {Sbornik. Mathematics},
     pages = {103--126},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {1970},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1970_10_1_a7/}
}