@inproceedings{børge1945mean,
title={Mean motions and zeros of almost periodic functions},
author={Børge Jessen, and Hans Tornehave},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203121071731656},
booktitle={Acta Mathematica},
volume={77},
number={1},
pages={137-279},
year={1945},
}
Børge Jessen, and Hans Tornehave. Mean motions and zeros of almost periodic functions. 1945. Vol. 77. In Acta Mathematica. pp.137-279. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203121071731656.