@article{JRAM_1933__169_149847,
     author = {Otto Volk},
     title = {\"Uber dreifache {Fl\"achensysteme,} die sich in {Geod\"atischen} schneiden.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {98--102},
     publisher = {mathdoc},
     volume = {169},
     year = {1933},
     zbl = {0006.32402},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1933__169_149847/}
}