1. D. Averna, G. Bonanno, A mountain pass theorem for a suitable class of functions, Rocky Mountain J. Math., in press.
2. A three critical points theorem and its applications to the ordinary Dirichlet problem;Averna;Topol. Methods Nonlinear Anal.,2003
3. Three solutions for a Neumann boundary value problem involving the p-Laplacian;Averna;Le Matematiche,2005
4. Analyse Functionelle – Théorie et Applications;Brézis,1983
5. Non-differentiable functionals and applications to elliptic problems with discontinuous nonlinearities;Bonanno;J. Differ. Equations,2008