@article{ZNSL_2014_422_a5,
     author = {S. A. Nazarov},
     title = {Gap opening around a~given point of the spectrum of a~cylindrical waveguide by means of gentle periodic perturbation of walls},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {90--130},
     year = {2014},
     volume = {422},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2014_422_a5/}
}