@inproceedings{vladimir2005elliptic,
title={Elliptic CR-manifolds and shear invariant ordinary differential equations with additional symmetries},
author={Vladimir Ezhov, and Gerd Schmalz},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203620757644922},
booktitle={Arkiv for Matematik},
volume={45},
number={2},
pages={253-268},
year={2005},
}
Vladimir Ezhov, and Gerd Schmalz. Elliptic CR-manifolds and shear invariant ordinary differential equations with additional symmetries. 2005. Vol. 45. In Arkiv for Matematik. pp.253-268. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203620757644922.