@article{DE_1991_27_11_a7,
     author = {D. S. Ushkho},
     title = {Limit cycles of an autonomous system with algebraic right-hand sides},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1915--1925},
     publisher = {mathdoc},
     volume = {27},
     number = {11},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_11_a7/}
}