@article{MAT_1969_13_1_a5,
     author = {L. V. H\"ormander},
     title = {On the characteristic {Cauchy} problem},
     journal = {Matematika},
     pages = {83--110},
     publisher = {mathdoc},
     volume = {13},
     number = {1},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1969_13_1_a5/}
}