@article{TRSPY_1951_38_a2,
     author = {S. N. Bernshtein},
     title = {On the best approximation of functions of several variables by means of polynomials or trigonometric sums},
     journal = {Informatics and Automation},
     pages = {24--29},
     publisher = {mathdoc},
     volume = {38},
     year = {1951},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1951_38_a2/}
}