Bifurcations élémentaires et transition G. Iooss (1979/1980) Séminaire Équations aux dérivées partielles (Polytechnique)
Bounded and almost automorphic solutions of a Liénard equation with a singular nonlinearity. Cieutat, P., Fatajou, S., N'guérékata, G.M. (2008) Electronic Journal of Qualitative Theory of Differential Equations [electronic only]
Boundeness and Stepanov's almost periodicity of solutions. Hu, Zuosheng (2005) Electronic Journal of Differential Equations (EJDE) [electronic only]