@article{DAN_1986_286_4_a0,
     author = {Yu. Sh. Abramov},
     title = {Two-parameter operator pencils of waveguide type},
     journal = {Doklady Akademii Nauk},
     pages = {777--781},
     year = {1986},
     volume = {286},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1986_286_4_a0/}
}