%0 Journal Article %A Guckenheimer, John %T Phase portraits of planar vector fields: Computer proofs. %J Experimental mathematics %D 1995 %P 153-165 %V 4 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/EXMA_1995__4_2_226090/ %G en %F EXMA_1995__4_2_226090