@article{DE_1992_28_8_a24,
     author = {Yu. V. Malyshev and V. P. Zakharov},
     title = {Quadratic systems with limit cycles},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1459--1461},
     publisher = {mathdoc},
     volume = {28},
     number = {8},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1992_28_8_a24/}
}