@article{JCA_2014_21_3_JCA_2014_21_3_a16,
     author = {F. Bigolin and A. Kozhevnikov},
     title = {Tangency, {Paratangency} and {Four-Cones} {Coincidence} {Theorem} in {Carnot} {Groups}},
     journal = {Journal of convex analysis},
     pages = {887--899},
     publisher = {mathdoc},
     volume = {21},
     number = {3},
     year = {2014},
     url = {http://geodesic.mathdoc.fr/item/JCA_2014_21_3_JCA_2014_21_3_a16/}
}