@inproceedings{a.1965quasi-analytic,
title={Quasi-analytic vectors},
author={A. E. Nussbaum},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203434712717047},
booktitle={Arkiv for Matematik},
volume={6},
number={2},
pages={179-191},
year={1965},
}