@article{MZ_1955__63_169539,
     author = {Hans Freudenthal},
     title = {Neuere {Fassungen} des {Riemann-Helmholtz-Lieschen} {Raumproblems.}},
     journal = {Mathematische Zeitschrift},
     pages = {374--405},
     year = {1955},
     volume = {63},
     zbl = {0074.36103},
     url = {http://geodesic.mathdoc.fr/item/MZ_1955__63_169539/}
}