@article{00923796, title = {Phase portraits of planar vector fields: Computer proofs.}, journal = {Experimental Mathematics}, volume = {4}, year = {1995}, pages = {153-165}, doi = {10.1080/10586458.1995.10504316}, zbl = {0856.34045}, language = {en}, url = {http://dml.mathdoc.fr/item/00923796} }
Guckenheimer, John. Phase portraits of planar vector fields: Computer proofs.. Experimental Mathematics, Tome 4 (1995) pp. 153-165. doi : 10.1080/10586458.1995.10504316. http://gdmltest.u-ga.fr/item/00923796/