@article{RMI_1994_1994_1_a11,
     author = {Koskela, Pekka},
     title = {Un lema inverso de {Sobolev.}},
     journal = {Revista matem\'atica iberoamericana},
     pages = {123-141},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {1994},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RMI_1994_1994_1_a11/}
}