@inproceedings{donald1970representation,
title={Representation of turing reducibility by word and conjugacy problems in finitely presented groups},
author={Donald J. Collins},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203224259978126},
booktitle={Acta Mathematica},
volume={128},
number={1},
pages={73-90},
year={1970},
}
Donald J. Collins. Representation of turing reducibility by word and conjugacy problems in finitely presented groups. 1970. Vol. 128. In Acta Mathematica. pp.73-90. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203224259978126.