@article{MAN_1926__95_159132,
     author = {E. Trefftz},
     title = {Zu den {Grundlagen} der {Schwingungstheorie}},
     journal = {Mathematische Annalen},
     pages = {307--312},
     publisher = {mathdoc},
     volume = {95},
     year = {1926},
     zbl = {51.0620.04},
     url = {http://geodesic.mathdoc.fr/item/MAN_1926__95_159132/}
}