@article{DE_1989_25_9_a8,
     author = {G. S. Osipenko},
     title = {Application of theorems on the perturbation of invariant manifolds},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1526--1532},
     year = {1989},
     volume = {25},
     number = {9},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_9_a8/}
}