@article{RLIN_2000_9_11_3_a1,
     author = {Monti, Roberto},
     title = {Some properties of {Carnot-Carath\'eodory} balls in the {Heisenberg} group},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Matematica e applicazioni},
     pages = {155--167},
     publisher = {mathdoc},
     volume = {Ser. 9, 11},
     number = {3},
     year = {2000},
     zbl = {1197.53064},
     mrnumber = {1325922},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLIN_2000_9_11_3_a1/}
}