@article{PMIHES_2011__113__1_0,
     author = {Heinonen, Juha and Keith, Stephen},
     title = {Flat forms, {bi-Lipschitz} parametrizations, and smoothability of manifolds},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {1--37},
     publisher = {Springer-Verlag},
     volume = {113},
     year = {2011},
     doi = {10.1007/s10240-011-0032-4},
     mrnumber = {2805596},
     zbl = {1238.30039},
     language = {en},
     url = {http://archive.numdam.org/articles/10.1007/s10240-011-0032-4/}
}