@article{IM_1985__82_143300,
     author = {P. Tukia},
     title = {Differentiability and rigidity of {M\"obius} groups.},
     journal = {Inventiones mathematicae},
     pages = {557--578},
     publisher = {mathdoc},
     volume = {82},
     year = {1985},
     zbl = {0564.30033},
     url = {http://geodesic.mathdoc.fr/item/IM_1985__82_143300/}
}