@article{DE_1994_30_5_a3,
     author = {N. N. Petrov},
     title = {Shortest {sub-Riemannian} geodesics},
     journal = {Differencialʹnye uravneni\^a},
     pages = {768--775},
     year = {1994},
     volume = {30},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1994_30_5_a3/}
}