@article{DE_1990_26_4_a17,
     author = {S. E. Pastukhova},
     title = {On the continuation of microlocal smoothness of solutions of boundary value problems for a second-order hyperbolic equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {692--699},
     publisher = {mathdoc},
     volume = {26},
     number = {4},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1990_26_4_a17/}
}