@article{DE_1970_6_5_a0,
     author = {I. S. Kukles and I. G. Rozet},
     title = {A certain case of generation of limit cycles on a plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {771--778},
     publisher = {mathdoc},
     volume = {6},
     number = {5},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_5_a0/}
}