@article{JRAM_1972__255_151236,
     author = {G\"unter Frank},
     title = {Zur {Zerlegung} linearer {Differentialoperatoren} mit ganzen {Koeffizienten.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {94--98},
     publisher = {mathdoc},
     volume = {255},
     year = {1972},
     zbl = {0243.34010},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1972__255_151236/}
}