@article{SM_1997_188_10_a3,
     author = {N. N. Pustovoitov},
     title = {Estimates of the~best approximations of periodic functions by trigonometric polynomials in terms of averaged differences and the~multidimensional {Jackson's} theorem},
     journal = {Sbornik. Mathematics},
     pages = {1507--1520},
     year = {1997},
     volume = {188},
     number = {10},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1997_188_10_a3/}
}