@article{GDZPPN002403668, title = {\"Uber das Spektrum positiver Operatoren.}, journal = {Mathematische Zeitschrift}, volume = {105}, year = {1968}, pages = {15-32}, zbl = {0179.18002}, url = {http://dml.mathdoc.fr/item/GDZPPN002403668} }
Lotz, Heinrich P. Über das Spektrum positiver Operatoren.. Mathematische Zeitschrift, Tome 105 (1968) pp. 15-32. http://gdmltest.u-ga.fr/item/GDZPPN002403668/