1. A note on uniqueness of Cauchy problems associated to planar Hamiltonian systems Portu - gal;Rebelo;Math,2000
2. Subharmonic solutions of second order nonlinear equations : a time - map ap - proach Nonlinear Subharmonic solutions of planar Hamiltonian systems Landesman - Lazer conditions for periodic boundary value problems with asymmetric nonlin - earities;Ding;Anal Differential Equations,1993
3. Maslov index Poincare - Birkhoff theorem and periodic solutions of asymptotically linear planar Hamiltonian systems;Margheri;Differential Equations,2002
4. On second order periodic symmetric differential systems having subharmon - ics of all sufficiently large orders;Cac;Differential Equations,1996
5. Subharmonic solutions for some second - order differential equations with singularities Siam;Fonda;Math Anal,1993