MathSciDoc: An Archive for Mathematician ∫

@inproceedings{sigurdur1963invariants,
  title={Invariants and fundamental functions},
  author={Sigurdur Helgason},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203201150795954},
  booktitle={Acta Mathematica},
  volume={109},
  number={1},
  pages={241-258},
  year={1963},
}