1. Periodic and subharmonic solutions for a class of second-order Hamiltonian systems;Avila;Dynam. Systems Appl.,1994
2. An existence criterion for the critical points on unbounded manifolds;Cerami;Istit. Lombardo Accad. Sci. Lett. Rend. A,1978
3. Nonlinear oscillations and boundary value problems for Hamiltonian systems;Clarke;Arch. Ration. Mech. Anal.,1982
4. Variational elliptic problems which are nonquadratic at infinity;Costa;Nonlinear Anal.,1994
5. Minimax principles for critical-point theory in applications to quasilinear boundary-value problems;El Amrouss;Electron. J. Differential Equations,2000