@article{DE_1977_13_3_a2,
     author = {M. V. Dolov},
     title = {Limit cycles and {Darboux} integrals in the case of a node},
     journal = {Differencialʹnye uravneni\^a},
     pages = {406--415},
     publisher = {mathdoc},
     volume = {13},
     number = {3},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_3_a2/}
}