@article{MABA_1990_4_3-4_a17,
     author = {S. N. Nikolskii},
     title = {Jackson's {Order} of {Approximation} in the {Problem} of {Approximation} of {Continuous} {Set-Valued} {Map}},
     journal = {Mathematica balkanica},
     pages = {396},
     year = {1990},
     volume = {4},
     number = {3-4},
     url = {http://geodesic.mathdoc.fr/item/MABA_1990_4_3-4_a17/}
}