@article{JRAM_1930__162_149712,
     author = {Heinrich Grell},
     title = {Zur {Normentheorie} in hyperkomplexen {Systemen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {60--62},
     year = {1930},
     volume = {162},
     zbl = {56.0868.02},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1930__162_149712/}
}