@inproceedings{patricia1983positive,
title={Positive solutions of elliptic equations in nondivergence form and their adjoints},
author={Patricia Bauman},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203517765368412},
booktitle={Arkiv for Matematik},
volume={22},
number={1},
pages={153-173},
year={1983},
}

Patricia Bauman. Positive solutions of elliptic equations in nondivergence form and their adjoints. 1983. Vol. 22. In Arkiv for Matematik. pp.153-173. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203517765368412.