@article{05847801, title = {Existence of positive solutions of nonlinear second-order periodic boundary value problems.}, journal = {Boundary Value Problems [electronic only]}, volume = {2010}, year = {2010}, doi = {10.1155/2010/626054}, zbl = {1219.34055}, language = {en}, url = {http://dml.mathdoc.fr/item/05847801} }
Ma, Ruyun; Gao, Chenghua; Chen, Ruipeng. Existence of positive solutions of nonlinear second-order periodic boundary value problems.. Boundary Value Problems [electronic only], Tome 2010 (2010) . doi : 10.1155/2010/626054. http://gdmltest.u-ga.fr/item/05847801/