@article{DAN_1978_239_4_a4,
     author = {V. Ya. Ivrii},
     title = {The propagation of singularities of a solution of the wave equation near a boundary},
     journal = {Doklady Akademii Nauk},
     pages = {772--774},
     publisher = {mathdoc},
     volume = {239},
     number = {4},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_239_4_a4/}
}