@article{MZM_2006_80_3_a4,
     author = {S. V. Galtsev and A. I. Shafarevich},
     title = {Spectrum and {Pseudospectrum} of non-self-adjoint {Schr\"odinger} {Operators} with {Periodic} {Coefficients}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {356--366},
     publisher = {mathdoc},
     volume = {80},
     number = {3},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2006_80_3_a4/}
}