@inproceedings{paolo1980a,
title={A note on Euler's ϕ-function},
author={Paolo Codecà},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203511132834357},
booktitle={Arkiv for Matematik},
volume={19},
number={1},
pages={261-263},
year={1980},
}