@article{DE_1969_5_7_a20,
     author = {M. V. Dolov},
     title = {The limit cycles of a certain class of differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1330--1334},
     publisher = {mathdoc},
     volume = {5},
     number = {7},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_7_a20/}
}