@article{05725777, title = {Existence of periodic solutions of linear Hamiltonian systems with sublinear perturbation.}, journal = {Boundary Value Problems [electronic only]}, volume = {2010}, year = {2010}, doi = {10.1155/2010/945421}, zbl = {1201.37093}, language = {en}, url = {http://dml.mathdoc.fr/item/05725777} }
Han, Zhiqing. Existence of periodic solutions of linear Hamiltonian systems with sublinear perturbation.. Boundary Value Problems [electronic only], Tome 2010 (2010) . doi : 10.1155/2010/945421. http://gdmltest.u-ga.fr/item/05725777/