@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}, }