@article{DE_1976_12_5_a14,
     author = {L. I. Zhilevich},
     title = {Conditions for the existence and uniqueness of a limit cycle for a certain two-dimensional differential system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {922--924},
     year = {1976},
     volume = {12},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1976_12_5_a14/}
}