@article{GDZPPN002107422,
title = {The pertubatively stable spectrum of a periodic Schr\"odinger operator.},
journal = {Inventiones mathematicae},
volume = {100},
year = {1990},
pages = {259-300},
zbl = {0701.34082},
url = {http://dml.mathdoc.fr/item/GDZPPN002107422}
}
Knörrer, H.; Feldman, J.; Trubowitz, E. The pertubatively stable spectrum of a periodic Schrödinger operator.. Inventiones mathematicae, Tome 100 (1990) pp. 259-300. http://gdmltest.u-ga.fr/item/GDZPPN002107422/