@inproceedings{jiri1990calibrations,
title={Calibrations and spinors},
author={Jiri Dadok, and F. Reese Harvey},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203319340900479},
booktitle={Acta Mathematica},
volume={170},
number={1},
pages={83-120},
year={1990},
}