@inproceedings{c.2012parallel,
title={PARALLEL TRACTOR EXTENSION AND AMBIENT METRICS OF HOLONOMY SPLIT G_2},
author={C. Robin Graham, and Travis Willse},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160914072625246779952},
booktitle={Journal of Differential Geometry},
volume={92},
number={3},
pages={463-505},
year={2012},
}

C. Robin Graham, and Travis Willse. PARALLEL TRACTOR EXTENSION AND AMBIENT METRICS OF HOLONOMY SPLIT G_2. 2012. Vol. 92. In Journal of Differential Geometry. pp.463-505. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20160914072625246779952.