@article{DE_1991_27_11_a16,
     author = {A. N. Novokhrost},
     title = {Limit cycles of a quadratic system that has a particular integral in the form of a parabola},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1981--1983},
     publisher = {mathdoc},
     volume = {27},
     number = {11},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_11_a16/}
}