@article{SM_2003_194_6_a3,
     author = {S. K. Vodop'yanov},
     title = {Differentiability of maps of  {Carnot} groups of {Sobolev} classes},
     journal = {Sbornik. Mathematics},
     pages = {857--877},
     publisher = {mathdoc},
     volume = {194},
     number = {6},
     year = {2003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2003_194_6_a3/}
}