We classify the phase portraits of the cubic systems in the plane such that they do not have finite critical points, and the critical points on the equator of the Poincaré sphere are isolated and have linear part non-identically zero.
@article{urn:eudml:doc:41107, title = {Chordal cubic systems.}, journal = {Publicacions Matem\`atiques}, volume = {33}, year = {1989}, pages = {253-311}, zbl = {0687.34038}, mrnumber = {MR1030968}, language = {en}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:41107} }
Carbonell, Marc; Llibre, Jaume. Chordal cubic systems.. Publicacions Matemàtiques, Tome 33 (1989) pp. 253-311. http://gdmltest.u-ga.fr/item/urn:eudml:doc:41107/