MathSciDoc: An Archive for Mathematician ∫

@inproceedings{donald1968recursively,
  title={Recursively enumerable degrees and the conjugacy problem},
  author={Donald J. Collins},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203216494260069},
  booktitle={Acta Mathematica},
  volume={122},
  number={1},
  pages={115-160},
  year={1968},
}