@article{DE_1998_34_4_a1,
     author = {E. A. Andronova},
     title = {Partition of the parameter space of a quadratic system with a triple focus or a center at the origin},
     journal = {Differencialʹnye uravneni\^a},
     pages = {441--450},
     publisher = {mathdoc},
     volume = {34},
     number = {4},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1998_34_4_a1/}
}