@article{DE_1977_13_5_a22,
     author = {A. A. Shestakov},
     title = {Tests for the instability of a set with respect to a nonautonomous differential system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {958--960},
     publisher = {mathdoc},
     volume = {13},
     number = {5},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_5_a22/}
}