@article{MAN_1873__6_156626,
     author = {Sturm},
     title = {Das {Problem} der r\"aumlichen {Projectivit\"at.}},
     journal = {Mathematische Annalen},
     pages = {513--550},
     publisher = {mathdoc},
     volume = {6},
     year = {1873},
     zbl = {06.0375.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1873__6_156626/}
}