@misc{indiciaea2661fd6dad3,
  title = {Punished and unpunished responding in multiple variable-interval schedules.},
  author = {C Tullis and G Walters},
  year = {1968},
  doi = {10.1901/jeab.1968.11-147},
  url = {https://pubmed.ncbi.nlm.nih.gov/5645870/},
  note = {Source identifier: 5645870}
}