@inproceedings{karl1971propagation,
title={Propagation of analyticity of solutions of partial differential equations with constant coefficients},
author={Karl Gustav Andersson},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203445641179140},
booktitle={Arkiv for Matematik},
volume={8},
number={3},
pages={277-302},
year={1971},
}
Karl Gustav Andersson. Propagation of analyticity of solutions of partial differential equations with constant coefficients. 1971. Vol. 8. In Arkiv for Matematik. pp.277-302. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203445641179140.