@article{DE_1967_3_6_a0,
     author = {A. V. Kostin},
     title = {Asymptotic series in the theory of nonlinear systems of ordinary differential equations. {I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {875--889},
     year = {1967},
     volume = {3},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1967_3_6_a0/}
}