@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}, }