Fonda, AlessandroKlun, GiulianoSfecci, Andrea2019-09-122019-09-122019-09-12https://openscience.sissa.it/handle/1963/35339Dedicated to Shair Ahmad, on the occasion of his 85th birthdayWe prove the existence of periodic solutions of some infinite-dimensional nearly integrable Hamiltonian systems, bifurcating from infinite-dimensional tori, by the use of a generalization of the Poincaré–Birkhoff Theorem.enPeriodic solutions of nearly integrable Hamiltonian systems bifurcating from infinite-dimensional toriPreprint