© 2015 World Scientific Publishing Company. In this paper, we present the global phase portraits in the Poincaré disc of the planar quadratic polynomial systems which admit invariant straight lines with total multiplicity two and Darboux invariants.
- Darboux invariant
- phase portraits
- Quadratic vector fields
Llibre, J., & Oliveira, R. D. S. (2015). Quadratic systems with invariant straight lines of total multiplicity two having Darboux invariants. Communications in Contemporary Mathematics, 17(3), . https://doi.org/10.1142/S0219199714500187