@inproceedings{jan1964on,
title={On the propagation of analyticity of solutions of differential equations with constant coefficients},
author={Jan Boman},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203431265700017},
booktitle={Arkiv for Matematik},
volume={5},
number={3},
pages={271-279},
year={1964},
}
Jan Boman. On the propagation of analyticity of solutions of differential equations with constant coefficients. 1964. Vol. 5. In Arkiv for Matematik. pp.271-279. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203431265700017.