@article{GDZPPN002285320,
title = {Singul\"are elliptische Differentialoperatoren in Hilbertschen R\"aumen.},
journal = {Mathematische Annalen},
volume = {132},
year = {1956},
pages = {150-176},
zbl = {0070.34603},
url = {http://dml.mathdoc.fr/item/GDZPPN002285320}
}
Stummel, F. Singuläre elliptische Differentialoperatoren in Hilbertschen Räumen.. Mathematische Annalen, Tome 132 (1956) pp. 150-176. http://gdmltest.u-ga.fr/item/GDZPPN002285320/