@article{DE_1968_4_5_a2,
     author = {Ya. Kurzweil},
     title = {Invariant sets of differential systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {785--797},
     publisher = {mathdoc},
     volume = {4},
     number = {5},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_5_a2/}
}