@article{DE_1987_23_12_a6,
     author = {V. V. Filippov},
     title = {On a theorem of {Kneser}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2068--2074},
     publisher = {mathdoc},
     volume = {23},
     number = {12},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_12_a6/}
}