@article{DE_1968_4_12_a13,
     author = {L. A. Cherkas},
     title = {The singular cycles of the equation $\frac{dy}{dx}=\frac{P(x,y)}{xy}$, where $P(x,y)$, is a second degree polynomial},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2281--2285},
     publisher = {mathdoc},
     volume = {4},
     number = {12},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_12_a13/}
}