@article{DE_2003_39_3_a20,
     author = {V. V. Filippov},
     title = {A {Remark} on the {Existence} of a {Periodic} {Solution}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {425--427},
     year = {2003},
     volume = {39},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2003_39_3_a20/}
}