@article{DE_1981_17_5_a25,
     author = {E. B. Frolov},
     title = {A criterion for the attainability of nonlinear systems given on manifolds},
     journal = {Differencialʹnye uravneni\^a},
     pages = {944--948},
     year = {1981},
     volume = {17},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_5_a25/}
}