1. A multiplicity result for a class of elliptic boundary value problems;Amann;Proc. Roy. Soc. Edinburgh A,1979
2. On the inversion of some differentiable mappings with singularities between Banach Spaces;Ambrosetti;Ann. Math. Pura Appl.,1973
3. Inclusions for eigenvalues of selfadjoint problems;Behnke,1994
4. R.L. Burden, J.D. Faires, Numerical Analysis, PWS-Kent, Boston, MA, 1989.
5. A. Castro, S. Gadam, The Lazer–McKenna conjecture for radial solutions in the Rn ball, Electron. J. Differential Equations (1993) 1–6.