@misc{heidrichmeisner2020proton,
  title={Proton-proton collisional age to order solar wind types},
  author={Verena Heidrich-Meisner and Lars Berger and Robert F. Wimmer-Schweingruber},
  year={2020},
  eprint={2003.10851},
  archivePrefix={arXiv},
  primaryClass={astro-ph.SR},
  doi={10.1051/0004-6361/201937378},
  url={https://arxiv.org/abs/2003.10851}
}