@article{JRAM_1927__158_149638,
     author = {F. Hausdorff},
     title = {Lipschitze {Zahlensysteme} und {Studysche} {Nablafunktionen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {113--127},
     publisher = {mathdoc},
     volume = {158},
     year = {1927},
     zbl = {53.0120.02},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1927__158_149638/}
}