@article{GDZPPN00206538X,
title = {Gaps and bands of one dimensional periodic Schr\"odinger operators.},
journal = {Commentarii mathematici Helvetici},
volume = {59},
year = {1984},
pages = {258-312},
zbl = {0554.34013},
url = {http://dml.mathdoc.fr/item/GDZPPN00206538X}
}
Garnett, J.; Trubowitz, Eugene. Gaps and bands of one dimensional periodic Schrödinger operators.. Commentarii mathematici Helvetici, Tome 59 (1984) pp. 258-312. http://gdmltest.u-ga.fr/item/GDZPPN00206538X/