@article{TMF_2007_151_2_a2,
     author = {D. I. Borisov},
     title = {Some singular perturbations of periodic operators},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {207--218},
     year = {2007},
     volume = {151},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2007_151_2_a2/}
}