1. Non–algebraic limit cycles for parametrized planar polynomial systems;Al-Dosary;Int. J. Math.,2007
2. Quadratic planar differential systems with algebraic limit cycles via quadratic plane cremona maps;Alberich-Carramiñana,2019
3. Theory of Oscillations;Andronov,1966
4. Piecewise linear differential systems with two real saddles;Artés;Math. Comput. Simulation,2013
5. Estimation of the number of algebraic limit cycles of the system x′=P(x,y), y′=Q(x,y) with algebraic right-hand sides;Bautin;(Russian) Differentsial’nye Uravneniya,1980