@inproceedings{kristian1999on,
title={On Gröchenig, Heil, and Walnut's proof of the local three squares theorem},
author={Kristian Seip},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203558228655741},
booktitle={Arkiv for Matematik},
volume={38},
number={1},
pages={93-96},
year={1999},
}
Kristian Seip. On Gröchenig, Heil, and Walnut's proof of the local three squares theorem. 1999. Vol. 38. In Arkiv for Matematik. pp.93-96. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203558228655741.