@article{GDZPPN002207842,
title = {Gap-bifurcation for nonlinear perturbations of Hill's equation.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {405},
year = {1990},
pages = {23-52},
zbl = {0704.34012},
url = {http://dml.mathdoc.fr/item/GDZPPN002207842}
}
Stuart, Charles A.; Küpper, T. Gap-bifurcation for nonlinear perturbations of Hill's equation.. Journal für die reine und angewandte Mathematik, Tome 405 (1990) pp. 23-52. http://gdmltest.u-ga.fr/item/GDZPPN002207842/