Periodic Solutions of Hamiltonian Systems
Yanheng Ding, Cheng Lee · SIAM Journal on Mathematical Analysis · 2000
Two sequences of periodic solutions with large and small norms, respectively, are obtained for Hamiltonian systems of the type \[ -\cj\dot{z}=\xi F_z(t, z)+\eta G_z(t, z), \] where F is superquadratic at $z=\iiff$ and G is subquadratic at z=0.