@article{DE_1984_20_5_a6,
     author = {D. S. Ushkho},
     title = {Qualitative investigation of a system with three centers},
     journal = {Differencialʹnye uravneni\^a},
     pages = {797--801},
     year = {1984},
     volume = {20},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1984_20_5_a6/}
}