@article{DAN_1980_252_5_a21,
     author = {Yu. V. Shestopalov},
     title = {Spectral properties of a class of non-self-adjoint boundary-value problems for systems of {Helmholtz} equations},
     journal = {Doklady Akademii Nauk},
     pages = {1108--1111},
     publisher = {mathdoc},
     volume = {252},
     number = {5},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_252_5_a21/}
}