@article{ZVMMF_1992_32_4_a7,
     author = {G. V. Alekseev and E. G. Komarov},
     title = {The non-self-conjugate singular spectral problem for a {Helmholtz} operator with discontinuous coefficients},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {587--597},
     year = {1992},
     volume = {32},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1992_32_4_a7/}
}