@article{DAN_1978_241_3_a8,
     author = {V. Ya. Ivrii},
     title = {Propagation of singularities of a solution of the wave equation in a domain having angular points},
     journal = {Doklady Akademii Nauk},
     pages = {536--539},
     publisher = {mathdoc},
     volume = {241},
     number = {3},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_241_3_a8/}
}