@article{TMF_2012_173_1_a6,
     author = {R. R. Gadyl'shin and I. Kh. Khusnullin},
     title = {Perturbation of a~periodic operator by a~narrow potential},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {127--134},
     publisher = {mathdoc},
     volume = {173},
     number = {1},
     year = {2012},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2012_173_1_a6/}
}