@article{ZNSL_2018_471_a11,
     author = {S. A. Nazarov},
     title = {Asymptotics of eigenvalues in spectral gaps of periodic waveguides with small singular perturbations},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {168--210},
     publisher = {mathdoc},
     volume = {471},
     year = {2018},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2018_471_a11/}
}