@article{MZ_1930__32_168257,
     author = {G., Hanke},
     title = {Au{\ss}erwesentliche {Singularit\"aten} linearer {Differentialgleichungen}},
     journal = {Mathematische Zeitschrift},
     pages = {751--762},
     publisher = {mathdoc},
     volume = {32},
     year = {1930},
     zbl = {56.1043.03},
     url = {http://geodesic.mathdoc.fr/item/MZ_1930__32_168257/}
}