@article{JRAM_1932__167_149806,
     author = {\"Oystein Ore},
     title = {Formale {Theorie} der linearen {Differentialgleichungen.} {(Erster} {Teil).}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {221--234},
     publisher = {mathdoc},
     volume = {167},
     year = {1932},
     zbl = {0003.20104},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1932__167_149806/}
}