1. Lusternik–Schnirelman theory and nonlinear eigenvalue problems;Amann;Math. Ann.,1972
2. Introduction to Banach Spaces and Their Geometry;Beauzamy,1982
3. Functional Analysis, Sobolev Spaces and Partial Differential Equations;Brezis,2011
4. Elliptic Partial Differential Equations of Second Order;Gilbarg,1977
5. On a nonlinear elliptic eigenvalue problem;Li;J. Differential Equations,1995