1. H. Amann and E. Zehnder, Non-trivial solutions for a class of non-resonance problems and applications to non-linear differential equations, to appear.
2. H. Amann and E. Zehnder, Multiple solutions for a class of non resonance problems and applications to differential equations, to appear.
3. On the inversion of some differentiable mappings with singularities between Banach spaces;Ambrosetti;Ann. Mat. Pura Appl.,1972
4. H. Berestycki, Le nombre de solutions de certains problèmes semi-linéaires elliptiques, to appear.
5. On some nonlinear Sturm-Lionville problems;Berestycki;J. Differential Equations,1977