@inproceedings{henry1977cocycles,
title={Cocycles and spectra},
author={Henry Helson, and William Parry},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203503539216292},
booktitle={Arkiv for Matematik},
volume={16},
number={1},
pages={195-206},
year={1977},
}