@article{1077379127,
author = {Nussbaum, Roger D.},
title = {The radius of the essential spectrum},
journal = {Duke Math. J.},
volume = {37},
number = {1},
year = {1970},
pages = { 473-478},
language = {en},
url = {http://dml.mathdoc.fr/item/1077379127}
}
Nussbaum, Roger D. The radius of the essential spectrum. Duke Math. J., Tome 37 (1970) no. 1, pp. 473-478. http://gdmltest.u-ga.fr/item/1077379127/