@article{1077465062,
author = {Hoffman, A. J. and Wielandt, H. W.},
title = {The variation of the spectrum of a normal matrix},
journal = {Duke Math. J.},
volume = {20},
number = {1},
year = {1953},
pages = { 37-39},
language = {en},
url = {http://dml.mathdoc.fr/item/1077465062}
}
Hoffman, A. J.; Wielandt, H. W. The variation of the spectrum of a normal matrix. Duke Math. J., Tome 20 (1953) no. 1, pp. 37-39. http://gdmltest.u-ga.fr/item/1077465062/