@article{01683047, title = {On spectra of geometric operators on open manifolds and differentiable groupoids.}, journal = {Electronic Research Announcements of the American Mathematical Society [electronic only]}, volume = {7}, year = {2001}, pages = {45-53}, doi = {10.1090/S1079-6762-01-00093-2}, zbl = {0983.58012}, language = {en}, url = {http://dml.mathdoc.fr/item/01683047} }
Lauter, Robert; Nistor, Victor. On spectra of geometric operators on open manifolds and differentiable groupoids.. Electronic Research Announcements of the American Mathematical Society [electronic only], Tome 7 (2001) pp. 45-53. doi : 10.1090/S1079-6762-01-00093-2. http://gdmltest.u-ga.fr/item/01683047/