@article{DE_1983_19_9_a27,
     author = {M. M. Khapaev and O. P. Filatov},
     title = {The averaging principle for systems with {\textquotedblleft}fast{\textquotedblright} and {\textquotedblleft}slow{\textquotedblright} variables},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1640--1643},
     year = {1983},
     volume = {19},
     number = {9},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1983_19_9_a27/}
}