@article{TM_1987_180_a48,
     author = {M. I. Ganzburg},
     title = {A~direct and inverse theorem on approximation by polynomials on the $m$- dimensional ball},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {91--92},
     year = {1987},
     volume = {180},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1987_180_a48/}
}