@article{MAN_1922__86_158932,
     author = {G. Hamel},
     title = {\"Uber erzwungene {Schwingungen} bei endlichen {Amplituden}},
     journal = {Mathematische Annalen},
     pages = {1--13},
     publisher = {mathdoc},
     volume = {86},
     year = {1922},
     zbl = {48.0519.03},
     url = {http://geodesic.mathdoc.fr/item/MAN_1922__86_158932/}
}