@article{RCM_1973__7_181599,
     author = {Gaston Demar\`ee and Diego Escobar C.},
     title = {Algunos aspectos num\'ericos de la ecuaci\'on deiferencial de {Duffing}},
     journal = {Revista colombiana de matematicas},
     pages = {45--52},
     publisher = {mathdoc},
     volume = {7},
     year = {1973},
     url = {http://geodesic.mathdoc.fr/item/RCM_1973__7_181599/}
}