@article{DAN_1987_294_6_a5,
     author = {S. V. Emel'yanov and S. K. Korovin and S. V. Nikitin},
     title = {Criteria for controllability of two-dimensional nonlinear systems},
     journal = {Doklady Akademii Nauk},
     pages = {1310--1314},
     publisher = {mathdoc},
     volume = {294},
     number = {6},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_294_6_a5/}
}