@inproceedings{richard1972on,
title={On the least$K$-th power non-residue},
author={Richard H. Hudson},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203454178577211},
booktitle={Arkiv for Matematik},
volume={12},
number={1},
pages={217-220},
year={1972},
}