@article{MZ_1974__137_172058,
     author = {Jochen Br\"uning},
     title = {Zur {Absch\"atzung} der {Spektralfunktion} elliptischer {Operatoren.}},
     journal = {Mathematische Zeitschrift},
     pages = {75--86},
     publisher = {mathdoc},
     volume = {137},
     year = {1974},
     zbl = {0268.47053},
     url = {http://geodesic.mathdoc.fr/item/MZ_1974__137_172058/}
}