@inproceedings{lars1988global,
title={Global parametrices for fundamental solutions of first order pseudo-differential hyperbolic operators},
author={Lars Gärding},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203531523773527},
booktitle={Arkiv for Matematik},
volume={28},
number={1},
pages={101-109},
year={1988},
}
Lars Gärding. Global parametrices for fundamental solutions of first order pseudo-differential hyperbolic operators. 1988. Vol. 28. In Arkiv for Matematik. pp.101-109. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203531523773527.