MathSciDoc: An Archive for Mathematician ∫

@inproceedings{,
  title={Richard Birkeland},
  author={},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203051982315432},
  booktitle={Acta Mathematica},
  volume={53},
  number={1},
  pages={I-IV},
  year={1929},
}