@inproceedings{walter1956the,
title={The automorphisms and the endomorphisms of the group algebra of the unit circle},
author={Walter Rudin},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203144143013828},
booktitle={Acta Mathematica},
volume={95},
number={1},
pages={39-55},
year={1956},
}
Walter Rudin. The automorphisms and the endomorphisms of the group algebra of the unit circle. 1956. Vol. 95. In Acta Mathematica. pp.39-55. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203144143013828.