@InProceedings{karvonen:empiricalmodels,
  title={Categories of Empirical Models},
  author={Karvonen, Martti},
  series = {Electronic Proceedings in Theoretical Computer Science},
  booktitle = {Proceedings of QPL 2018},
  year = {2018},
  volume = {287},
  pages = {239--252},
  DOI ={10.4204/EPTCS.287.14}
}