1. R. M. Bulatovich,On the continuability of a gyroscopic integral from a linear system to a nonlinear system, Teor. Primen. Meh.21 (1995), 1–7.
2. J. Chavarriga, J. Llibre andJ. Sotomayor,Algebraic solutions for polynomial systems with emphasis in the quadratic case, Exp. Math.15 (1997), 161–173.
3. C. Christopher andJ. Llibre,Integrability via invariant algebraic curves for planar polynomial differential systems, Ann. of Differential Equations16 (2000), 5–19.
4. C. Christopher, J. Llibre and J. V. Pereira,Multiplicity of invariant algebraic curves and Darboux integrability, Preprint 2000.
5. G. Darboux,Memoire sur les équations differentielles algébrique du premier ordre et du premier degré (Mélanges), Bull. Sci. Math. 2ème série2 (1878), 60–96, 123–144, 151–200.