@article{ambühl_ockenfels_roth_2020, 
  title={Payment in challenge studies from an economics perspective}, 
  DOI={10.5167/uzh-193050}, 
  publisher={BMJ Publishing Group}, 
  author={Ambühl, Sandro and Ockenfels, Axel and Roth, Alvin E}, 
  year={2020}, 
  month={Nov}
  }