@inproceedings{katsuju1989characteristic,
title={Characteristic Cauchy problems and analytic continuation of holomorphic solutions},
author={Katsuju Igari},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203533326891542},
booktitle={Arkiv for Matematik},
volume={28},
number={1},
pages={289-300},
year={1989},
}
Katsuju Igari. Characteristic Cauchy problems and analytic continuation of holomorphic solutions. 1989. Vol. 28. In Arkiv for Matematik. pp.289-300. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203533326891542.