MathSciDoc: An Archive for Mathematician ∫

@inproceedings{j.1930remarques,
  title={Remarques géométriques sur les enveloppes et la propagation des ondes},
  author={J. Hadamard},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203054259760451},
  booktitle={Acta Mathematica},
  volume={54},
  number={1},
  pages={247-261},
  year={1930},
}