MathSciDoc: An Archive for Mathematician ∫

@inproceedings{ole1976the,
  title={The inverse Sturm-Liouville problem with symmetric potentials},
  author={Ole H. Hald},
  url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170108203247455720249},
  booktitle={Acta Mathematica},
  volume={141},
  number={1},
  pages={263-291},
  year={1976},
}