@article{MZ_1939__45_168870,
     author = {F., Klein-Barmen},
     title = {Zur {Theorie} der {Gef\"uge} und {Vereine}},
     journal = {Mathematische Zeitschrift},
     pages = {595--606},
     publisher = {mathdoc},
     volume = {45},
     year = {1939},
     zbl = {0022.00701},
     url = {http://geodesic.mathdoc.fr/item/MZ_1939__45_168870/}
}