@article{05312504, title = {Existence theorems of periodic solutions for second-order nonlinear difference equations.}, journal = {Advances in Difference Equations [electronic only]}, volume = {2008}, year = {2008}, doi = {10.1155/2008/247071}, zbl = {1146.39006}, language = {en}, url = {http://dml.mathdoc.fr/item/05312504} }
Cai, Xiaochun; Yu, Jianshe. Existence theorems of periodic solutions for second-order nonlinear difference equations.. Advances in Difference Equations [electronic only], Tome 2008 (2008) . doi : 10.1155/2008/247071. http://gdmltest.u-ga.fr/item/05312504/