@article{SM_1992_72_1_a5,
     author = {M. Babayev},
     title = {On the degree of approximation of the {Sobolev} class~$W_q^r$ by bilinear forms in~$L_p$ for $1\leqslant q\leqslant p\leqslant 2$},
     journal = {Sbornik. Mathematics},
     pages = {113--120},
     publisher = {mathdoc},
     volume = {72},
     number = {1},
     year = {1992},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1992_72_1_a5/}
}