@inproceedings{alfred1951$p$-rings,
title={$p$-Rings and their Boolean-vector representation},
author={Alfred L. Foster},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203130328596723},
booktitle={Acta Mathematica},
volume={84},
number={1},
pages={231-261},
year={1951},
}