@article{MAN_1909__66_158376,
     author = {Georg Landsberg},
     title = {\"Uber die {Klasse} der {Fl\"achen,} welche ein {Strahlenb\"undel} unter festem {Winkel} schneiden},
     journal = {Mathematische Annalen},
     pages = {195--200},
     publisher = {mathdoc},
     volume = {66},
     year = {1909},
     zbl = {39.0711.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1909__66_158376/}
}