@article{SM_2006_197_3_a6,
     author = {I. I. Sharapudinov},
     title = {Approximation properties of mixed series in terms of {Legendre} polynomials on the classes~$W^r$},
     journal = {Sbornik. Mathematics},
     pages = {433--452},
     publisher = {mathdoc},
     volume = {197},
     number = {3},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_3_a6/}
}