@article{DE_1996_32_5_a21,
     author = {A. S. Shube},
     title = {On the structure of an integrating factor for a cubic system with a singular point of center type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {713--715},
     publisher = {mathdoc},
     volume = {32},
     number = {5},
     year = {1996},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1996_32_5_a21/}
}