@article{DE_1987_23_5_a14,
     author = {L. A. Cherkas},
     title = {Limit cycles of autonomous systems with phase space $\mathbf C^2$},
     journal = {Differencialʹnye uravneni\^a},
     pages = {848--851},
     publisher = {mathdoc},
     volume = {23},
     number = {5},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_5_a14/}
}