@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/}
}