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@article{DE_1985_21_4_a14, author = {M. P. Grigolia}, title = {A generalization of the characteristic problem for hyperbolic systems}, journal = {Differencialʹnye uravneni\^a}, pages = {678--686}, publisher = {mathdoc}, volume = {21}, number = {4}, year = {1985}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1985_21_4_a14/} }
M. P. Grigolia. A generalization of the characteristic problem for hyperbolic systems. Differencialʹnye uravneniâ, Tome 21 (1985) no. 4, pp. 678-686. http://geodesic.mathdoc.fr/item/DE_1985_21_4_a14/