@article{PORMA_1990__47_4_115732,
     author = {Ramos, M.},
     title = {Periodic solutions of higher order ordinary differential equations with one-sided growth restrictions on the nonlinear term},
     journal = {Portugaliae mathematica},
     pages = {431--436},
     publisher = {mathdoc},
     volume = {47},
     number = {4},
     year = {1990},
     mrnumber = {1090481},
     zbl = {0714.34068},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1990__47_4_115732/}
}