@article{DAN_1992_322_1_a9,
     author = {T. V. Savina and B. Yu. Sternin and V. E. Shatalov},
     title = {On the reflection law for the {Helmholtz} equation},
     journal = {Doklady Akademii Nauk},
     pages = {48--51},
     publisher = {mathdoc},
     volume = {322},
     number = {1},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_322_1_a9/}
}