@article{ZVMMF_2003_43_7_a9,
     author = {A. N. Bogolyubov and M. D. Malykh},
     title = {On the perturbation theory of spectral characteristics of waveguides},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {1049--1061},
     year = {2003},
     volume = {43},
     number = {7},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_2003_43_7_a9/}
}