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@article{DAN_1971_197_3_a2, author = {V. Ya. Ivrii}, title = {The {Cauchy} problem for nonstrictly hyperbolic equations}, journal = {Doklady Akademii Nauk}, pages = {517--519}, publisher = {mathdoc}, volume = {197}, number = {3}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1971_197_3_a2/} }
V. Ya. Ivrii. The Cauchy problem for nonstrictly hyperbolic equations. Doklady Akademii Nauk, Tome 197 (1971) no. 3, pp. 517-519. http://geodesic.mathdoc.fr/item/DAN_1971_197_3_a2/