@article{MZ_1949__51_169065,
     author = {W., SCHWAN},
     title = {Perspektivit\"aten in allgemeinen {Verb\"anden}},
     journal = {Mathematische Zeitschrift},
     pages = {126--134},
     publisher = {mathdoc},
     volume = {51},
     year = {1949},
     zbl = {0030.19701},
     url = {http://geodesic.mathdoc.fr/item/MZ_1949__51_169065/}
}