@article{TMF_1997_110_3_a7,
     author = {Yu. P. Chuburin},
     title = {On small perturbations of the {Schr\"odinger} equation with periodic potential},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {443--453},
     year = {1997},
     volume = {110},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1997_110_3_a7/}
}