@article{IM2_1973_7_2_a6,
     author = {Yu. A. Brudnyi and M. I. Ganzburg},
     title = {On an extremal problem for polynomials in~$n$ variables},
     journal = {Izvestiya. Mathematics},
     pages = {345--356},
     year = {1973},
     volume = {7},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1973_7_2_a6/}
}