1. Ambrosetti, A., Prodi, G.: A Primer of Nonlinear Analysis. Cambridge University Press, Cambridge (1993)
2. Carleson, L.: On convergence and growth of partial sums of Fourier series. Acta Math. 116, 135–157 (1966)
3. Crandall, M.G., Rabinowitz, P.H.: The Hopf Bifurcation Theorem. MRC Technical Summary Report, No.1604. University of Wisconsin Mathematics Research Center (1976)
4. Evans, L.C.: Partial Differential Equations. American Mathematical Society, Providence (1998)
5. Gallego, F.B., Fajardo, J.C.V.: Bifurcations under nondegenerated conditions of higher degree and a new simple proof of the Hopf–Neimark–Sacker bifurcation theorem. J. Math. Anal. Appl. 237, 93–105 (1999)