@article{EJDE_1999__1999__a13,
     author = {Christopher,  Colin},
     title = {Liouvillian first integrals of second order polynomial differential equations},
     journal = {Electronic journal of differential equations},
     year = {1999},
     volume = {1999},
     zbl = {0939.34002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_1999__1999__a13/}
}