1. The Hopf Bifurcation and Its Applications;Marsden,1976
2. Bifurcation of periodic solutions;Cronin;J. Math. Anal. Appl.,1979
3. S. Hoyle, Local solution manifolds for nonlinear equations, Nonlinear Anal., Theory, Methods Appl., in press.
4. Topics in Nonlinear Functional Analysis;Nirenberg,1974