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@article{MAT_1957_1_1_a3, author = {Peter D. Lax}, title = {On {Cauchy's} problem for hyperbolic equations and the differentiability of solutions of elliptic equations}, journal = {Matematika}, pages = {43--59}, publisher = {mathdoc}, volume = {1}, number = {1}, year = {1957}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MAT_1957_1_1_a3/} }
Peter D. Lax. On Cauchy's problem for hyperbolic equations and the differentiability of solutions of elliptic equations. Matematika, Tome 1 (1957) no. 1, pp. 43-59. http://geodesic.mathdoc.fr/item/MAT_1957_1_1_a3/