@article{ZNSL_1985_147_a10,
     author = {Yu. G. Safarov},
     title = {On propagation of singularities of solutions of initial-boundary value problems for first order hyperbolic systems.},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {138--149},
     publisher = {mathdoc},
     volume = {147},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1985_147_a10/}
}