@article{DE_1988_24_6_a7,
     author = {G. S. Osipenko},
     title = {Perturbation of invariant manifolds. {IV}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {987--993},
     publisher = {mathdoc},
     volume = {24},
     number = {6},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1988_24_6_a7/}
}