@article{MAN_1931__104_159479,
     author = {A. Wald},
     title = {Axiomatik des {Zwischenbegriffes} in metrischen {R\"aumen}},
     journal = {Mathematische Annalen},
     pages = {476--484},
     publisher = {mathdoc},
     volume = {104},
     year = {1931},
     zbl = {57.0750.05},
     url = {http://geodesic.mathdoc.fr/item/MAN_1931__104_159479/}
}