@article{JRAM_1936__175_149965,
     author = {Hans Jonas},
     title = {Eine neue {Eigenschaft} der pseudosph\"arischen {Strahlenkongruenzen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {159--168},
     publisher = {mathdoc},
     volume = {175},
     year = {1936},
     zbl = {0014.17903},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1936__175_149965/}
}