@article{DE_1980_16_2_a19,
     author = {N. N. Bautin},
     title = {Estimation of the number of algebraic limit cycles of the system $\dot x=P(x,\,y)$, $\dot y=Q(x,\,y)$ with algebraic right-hand sides},
     journal = {Differencialʹnye uravneni\^a},
     pages = {362},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1980_16_2_a19/}
}