1. On matrices depending on parameters;Arnol’d;Russian Math. Surveys,1971
2. Geometrical Methods in the Theory of Ordinary Differential Equations;Arnol’d,1983
3. On Melnikov’s persistency problem;Bourgain;Math. Res. Lett.,1997
4. On a quasi-periodic Hopf bifurcation;Braaksma;Ann. Inst. H. Poincaré, Anal. Non Linéaire,1987
5. Toward a quasi-periodic bifurcation theory;Braaksma;Mem. Amer. Math. Soc.,1990