@article{MZ_1964__85_170305,
     author = {Klaus Habetha},
     title = {Regularit\"atsfragen beim {Phragm\'en-Lindel\"ofschen} {Prinzip} f\"ur elliptische {Differentialgleichungen.}},
     journal = {Mathematische Zeitschrift},
     pages = {291--313},
     publisher = {mathdoc},
     volume = {85},
     year = {1964},
     zbl = {0137.07002},
     url = {http://geodesic.mathdoc.fr/item/MZ_1964__85_170305/}
}