@article{10_4064_cm_83_2_209_216,
     author = {Thomas Friedrich},
     title = {A geometric estimate for a periodic {Schr\"odinger} operator},
     journal = {Colloquium Mathematicum},
     pages = {209--216},
     publisher = {mathdoc},
     volume = {83},
     number = {2},
     year = {2000},
     doi = {10.4064/cm-83-2-209-216},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-83-2-209-216/}
}