@inproceedings{linda1979local,
title={Local solvability of second order differential operators on nilpotent Lie groups},
author={Linda Preiss Rothschild},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203510176892349},
booktitle={Arkiv for Matematik},
volume={19},
number={1},
pages={145-175},
year={1979},
}
Linda Preiss Rothschild. Local solvability of second order differential operators on nilpotent Lie groups. 1979. Vol. 19. In Arkiv for Matematik. pp.145-175. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203510176892349.