@article{EJDE_2012__2012__a17,
     author = {Artes,  Joan C. and Llibre,  Jaume and Vulpe,  Nicolae},
     title = {Complete geometric invariant study of two classes of quadratic systems},
     journal = {Electronic journal of differential equations},
     year = {2012},
     volume = {2012},
     zbl = {1243.34044},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2012__2012__a17/}
}