1. Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions, I;Agmon;Comm. Pure Appl. Math.,1959
2. Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions, II;Agmon;Comm. Pure Appl. Math.,1964
3. Elementary critical point theory and perturbations of elliptic boundary value problems at resonance;Ahmad;Ind. Univ. Math. J.,1976
4. On the existence of multiple solutions for a class of nonlinear boundary value problems;Ambrosetti,1973
5. A. Ambrosetti and G. Mancini, Some remarks on nonlinear elliptic problems, in “Proceedings of a Seminar on Applications of Nonlinear Functional Analysis to Differential Equations,” to appear. Note added in proof. Prof. Vidossich has communicated to us that the Proceedings quoted in [4] will not appear.