@article{IVM_1978_1_a0,
     author = {M. D. Bronshtein and V. R. Fridlender},
     title = {A~characteristic {Cauchy} problem},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {3--7},
     publisher = {mathdoc},
     number = {1},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1978_1_a0/}
}