@inproceedings{h.1970the,
title={The homology groups of some ordered systems},
author={H. B. Griffiths},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203226240800138},
booktitle={Acta Mathematica},
volume={129},
number={1},
pages={195-235},
year={1970},
}