@article{DE_1969_5_7_a21,
     author = {N. I. Avdonin},
     title = {Examples of the generation of a limit cycle from a separatrix loop and a singular cycle},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1335--1337},
     publisher = {mathdoc},
     volume = {5},
     number = {7},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_7_a21/}
}