@article{DAN_1984_279_2_a0,
     author = {A. A. Agrachev and S. A. Vakhrameev},
     title = {Nonlinear control systems of constant rank and bang-bang},
     journal = {Doklady Akademii Nauk},
     pages = {265--269},
     year = {1984},
     volume = {279},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1984_279_2_a0/}
}