@article{JEMS_2003_5_1_a0,
     author = {Luca Capogna and Nicola Garofalo},
     title = {Regularity of minimizers of the calculus of variations in {Carnot} groups via hypoellipticity of systems of {H\"ormander} type},
     journal = {Journal of the European Mathematical Society},
     pages = {1--40},
     year = {2003},
     volume = {5},
     number = {1},
     doi = {10.1007/s100970200043},
     url = {http://geodesic.mathdoc.fr/articles/10.1007/s100970200043/}
}