@article{DE_1981_17_2_a1,
     author = {V. I. Danilyuk and K. S. Sibirskii},
     title = {Syzygies between centroaffine invariants of a quadratic differential system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {210--219},
     publisher = {mathdoc},
     volume = {17},
     number = {2},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_2_a1/}
}