@article{SM_1968_4_4_a0,
     author = {O. V. Besov and V. P. Il'in},
     title = {Natural extension of the class of regions in embedding theorems},
     journal = {Sbornik. Mathematics},
     pages = {445--456},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {1968},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1968_4_4_a0/}
}