@inproceedings{åke1974one-sided,
title={One-sided minima of indefinite binary quadratic forms and one-sided diophantine approximations},
author={Åke Lindgren},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203456831023233},
booktitle={Arkiv for Matematik},
volume={13},
number={1},
pages={287-302},
year={1974},
}
Åke Lindgren. One-sided minima of indefinite binary quadratic forms and one-sided diophantine approximations. 1974. Vol. 13. In Arkiv for Matematik. pp.287-302. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203456831023233.