@article{JRAM_1967__227_150801,
     author = {Lothar Jantscher},
     title = {Lineare {Schwingungsgleichungen} und {Hauptfunktionen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {50--73},
     publisher = {mathdoc},
     volume = {227},
     year = {1967},
     zbl = {0161.30103},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1967__227_150801/}
}