@article{10_4007_annals_2009_169_79,
     author = {Thomas Vogel},
     title = {Existence of {Engel} structures},
     journal = {Annals of mathematics},
     pages = {79--137},
     publisher = {mathdoc},
     volume = {169},
     number = {1},
     year = {2009},
     doi = {10.4007/annals.2009.169.79},
     mrnumber = {2480602},
     zbl = {1195.58005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4007/annals.2009.169.79/}
}