@article{DE_1974_10_5_a23,
     author = {L. A. Cherkas and L. I. Zhilevich},
     title = {\"Uber {Grenzzyklen} einer quadratischen {Differentialgleichung}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {947--949},
     year = {1974},
     volume = {10},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1974_10_5_a23/}
}