@article{DE_1981_17_6_a17,
     author = {I. V. Kuznetsova},
     title = {Averaging in multifrequency systems with lag},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1128--1131},
     year = {1981},
     volume = {17},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_6_a17/}
}