Ding, Wei et al., Existence of periodic solutions of sublinear Hamiltonian systems, Acta mathematica Sinica. English series (Print) , 32(5), 2016, pp. 621-632
The variational method is used to obtain some existence theorems of periodic solutions of sublinear systems with or not with impacts under suitable growth conditions. Compared with normal systems, impact systems need additional conditions to ensure the existence of periodic bouncing solutions.