1. Theorems of existence and multiplicity for nonlinear elliptic problems with noninvertible linear part;Ambrosetti;Ann. Sc. Norm. Super. Pisa Cl. Sci. (4),1978
2. Abstract critical point theorems and applications to some nonlinear problems with “strong” resonance at infinity;Bartolo;Nonlinear Anal.,1983
3. Characterizations of the ranges of some nonlinear operators and applications to boundary value problems;Brézis;Ann. Sc. Norm. Super. Pisa Cl. Sci. (4),1978
4. Isolated Invariant Sets and the Morse Index;Conley,1978
5. Global Attractors in Abstract Parabolic Problems;Cholewa,2000