@inproceedings{henry1958prediction,
title={Prediction theory and Fourier Series in several variables},
author={Henry Helson, and David Lowdenslager},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203150382734875},
booktitle={Acta Mathematica},
volume={99},
number={1},
pages={165-202},
year={1958},
}
Henry Helson, and David Lowdenslager. Prediction theory and Fourier Series in several variables. 1958. Vol. 99. In Acta Mathematica. pp.165-202. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203150382734875.