@article{MAN_1921__82_158852,
     author = {E. Trefftz},
     title = {Zur {Prandtlschen} {Tragfl\"achentheorie}},
     journal = {Mathematische Annalen},
     pages = {306--319},
     publisher = {mathdoc},
     volume = {82},
     year = {1921},
     zbl = {48.0971.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1921__82_158852/}
}