@article{JRAM_1964__0214_0215_150637,
     author = {Hans Rohrbach and J\"urgen Weis},
     title = {Zum finiten {Fall} des {Bertrandschen} {Postulats.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {432--440},
     publisher = {mathdoc},
     volume = {0214_0215},
     year = {1964},
     zbl = {0131.04403},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1964__0214_0215_150637/}
}