@article{IM_1992__110_2_144043,
     author = {G.D. Raikov},
     title = {Eigenvalue asymptotics for the {Schr\"odinger} operator with perturbed periodic potential.},
     journal = {Inventiones mathematicae},
     pages = {75--94},
     publisher = {mathdoc},
     volume = {110},
     number = {2},
     year = {1992},
     zbl = {0801.35095},
     url = {http://geodesic.mathdoc.fr/item/IM_1992__110_2_144043/}
}