@article{IM2_1997_61_4_a9,
     author = {S. L. Edelstein},
     title = {Asymptotic splitting of boundary-value problems for the {Helmholtz} equation in a~strip with ``permeable'' boundaries},
     journal = {Izvestiya. Mathematics },
     pages = {877--898},
     publisher = {mathdoc},
     volume = {61},
     number = {4},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1997_61_4_a9/}
}