1. Characterization of the ranges of some nonlinear operators and applications to boundary value problems;Brezis;Annali Scu. norm. sup. Pisa,1978
2. Existence and uniqueness for a variational hyperbolic system without resonance;Bates;Nonlinear Analysis,1980
3. On the unique solvability of semilinear operator equations in Hilbert spaces;Amann;J. Math. pures appl.,1982
4. Semilinear equations of gradient type in Hilbert spaces and applications to differential equations;Mawhin,1981
5. Conservative systems of semilinear wave equations with periodic-Dirichlet boundary conditions;Mawhin;J. diff. Eqns,1981