@article{GDZPPN002067420,
title = {On the periodic spectrum of the 1-dimensional Schr\"odinger operator.},
journal = {Commentarii mathematici Helvetici},
volume = {65},
year = {1990},
pages = {1-3},
zbl = {0703.34085},
url = {http://dml.mathdoc.fr/item/GDZPPN002067420}
}
Kappeler, Th. On the periodic spectrum of the 1-dimensional Schrödinger operator.. Commentarii mathematici Helvetici, Tome 65 (1990) pp. 1-3. http://gdmltest.u-ga.fr/item/GDZPPN002067420/