@article{MAN_1878__13_156796,
     author = {B\"acklund},
     title = {Ueber partielle {Differentialgleichungen} h\"oherer {Ordnung,} die intermedi\"are erste {Integrale} besitzen. {Zweite} {Abhandlung}},
     journal = {Mathematische Annalen},
     pages = {69--108},
     publisher = {mathdoc},
     volume = {13},
     year = {1878},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/MAN_1878__13_156796/}
}