@article{DE_1970_6_10_a17,
     author = {L. I. Zhilevich},
     title = {The uniqueness conditions for the limit cycle},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1888--1891},
     year = {1970},
     volume = {6},
     number = {10},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_10_a17/}
}