@inproceedings{lars1951linear,
title={Linear hyperbolic partial differential equations with constant coefficients},
author={Lars Gårding},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203130968324728},
booktitle={Acta Mathematica},
volume={85},
number={1},
pages={1-62},
year={1951},
}
Lars Gårding. Linear hyperbolic partial differential equations with constant coefficients. 1951. Vol. 85. In Acta Mathematica. pp.1-62. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203130968324728.