@article{MS2_1957__5_165654,
     author = {VIDAR THOM\'EE},
     title = {Estimates of the {Friedrichs-Lewy} type for mixed problems in the theory of linear hyperbolic differential equations in two independent variables},
     journal = {Mathematica Scandinavica},
     pages = {93--114},
     publisher = {mathdoc},
     volume = {5},
     year = {1957},
     zbl = {0078.08601},
     url = {http://geodesic.mathdoc.fr/item/MS2_1957__5_165654/}
}