@article{GDZPPN002208423,
title = {On the absolutely continuous spectrum of perturbed periodic Sturm-Liouville operators.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {416},
year = {1991},
pages = {1-24},
zbl = {0716.34028},
url = {http://dml.mathdoc.fr/item/GDZPPN002208423}
}
Stolz, Günter. On the absolutely continuous spectrum of perturbed periodic Sturm-Liouville operators.. Journal für die reine und angewandte Mathematik, Tome 416 (1991) pp. 1-24. http://gdmltest.u-ga.fr/item/GDZPPN002208423/