1. A Sturm-Liouville theorem for nonlinear elliptic partial differential equations;Berger, Melvyn S.;Ann. Scuola Norm. Sup. Pisa Cl. Sci. (3),1966
2. Nonlinear elliptic boundary value problems;Browder, Felix E.;Bull. Amer. Math. Soc.,1963
3. Variational methods for nonlinear elliptic eigenvalue problems;Browder, Felix E.;Bull. Amer. Math. Soc.,1965
4. Infinite dimensional manifolds and non-linear elliptic eigenvalue problems;Browder, Felix E.;Ann. of Math. (2),1965
5. S\'{e}minaire de Math\'{e}matiques Sup\'{e}rieures, No. 15 (\'{E}t\'{e};Browder, Felix E.,1966