@article{DE_2001_37_4_a4,
     author = {V. V. Filippov},
     title = {Remarks on {Guiding} {Functions} and {Periodic} {Solutions}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {458--469},
     year = {2001},
     volume = {37},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2001_37_4_a4/}
}