@article{DE_1986_22_11_a27,
     author = {L. A. Cherkas},
     title = {Absence of limit cycles around a triple focus in a quadratic system in a plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2015--2017},
     publisher = {mathdoc},
     volume = {22},
     number = {11},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1986_22_11_a27/}
}