@article{MAN_1928__98_159204,
     author = {P. Urysohn and P. Alexandroff},
     title = {\"Uber nulldimensionale {Punktmengen}},
     journal = {Mathematische Annalen},
     pages = {89--106},
     publisher = {mathdoc},
     volume = {98},
     year = {1928},
     zbl = {53.0559.01},
     url = {http://geodesic.mathdoc.fr/item/MAN_1928__98_159204/}
}