@article{JRAM_1932__168_149838,
     author = {Oystein Ore},
     title = {Formale {Theorie} der linearen {Differentialgleichungen.} {(Zweiter} {Teil).}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {233--252},
     publisher = {mathdoc},
     volume = {168},
     year = {1932},
     zbl = {0005.39601},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1932__168_149838/}
}