@article{MAN_1978__236_163175,
     author = {William C. Lyford},
     title = {Spectral {Analysis} of the {Laplacian} in {Distorted} {Periodic} {Waveguides.}},
     journal = {Mathematische Annalen},
     pages = {255--284},
     publisher = {mathdoc},
     volume = {236},
     year = {1978},
     zbl = {0399.35082},
     url = {http://geodesic.mathdoc.fr/item/MAN_1978__236_163175/}
}