@article{alessandretti2018evidence,
  title={Evidence for a conserved quantity in human mobility},
  author={Alessandretti, Laura and Sapiezynski, Piotr and Sekara, Vedran and Lehmann, Sune and Baronchelli, Andrea},
  journal={Nature human behaviour},
  volume={2},
  number={7},
  pages={485},
  year={2018},
  publisher={Nature Publishing Group}
}