@article{DE_1979_15_8_a9,
     author = {E. P. Sobolevskii},
     title = {An averaging principle and stability of differential equations with a small parameter},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1444--1449},
     publisher = {mathdoc},
     volume = {15},
     number = {8},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1979_15_8_a9/}
}