@article{MAN_1982__259_163617,
     author = {T. Udim},
     title = {\"Uber das {Fehlen} positiver {Eigenwerte} bei einer {Klasse} elliptischer {Differential|operatoren.}},
     journal = {Mathematische Annalen},
     pages = {71--78},
     year = {1982},
     volume = {259},
     zbl = {0501.35024},
     url = {http://geodesic.mathdoc.fr/item/MAN_1982__259_163617/}
}