TY - JOUR T1 - Periodic Solutions of Second-Order Differential Equations in Hilbert Spaces Y1 - 2021 A1 - Alessandro Fonda A1 - Giuliano Klun A1 - Andrea Sfecci AB -

We prove the existence of periodic solutions of some infinite-dimensional systems by the use of the lower/upper solutions method. Both the well-ordered and non-well-ordered cases are treated, thus generalizing to systems some well-established results for scalar equations.

VL - 18 SN - 1660-5454 UR - https://doi.org/10.1007/s00009-021-01857-8 IS - 5 JO - Mediterranean Journal of Mathematics ER -