@article{DE_1968_4_4_a2,
     author = {N. N. Petrov},
     title = {Controllability of autonomous systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {606--617},
     publisher = {mathdoc},
     volume = {4},
     number = {4},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_4_a2/}
}