@article{MAN_1934__109_159694,
     author = {O. Danielsson},
     title = {S\"atze \"uber {Scharen} von {Fl\"achen} zweiter {Ordnung.}},
     journal = {Mathematische Annalen},
     pages = {521--524},
     publisher = {mathdoc},
     volume = {109},
     year = {1934},
     zbl = {0009.08201},
     url = {http://geodesic.mathdoc.fr/item/MAN_1934__109_159694/}
}