@misc{indiciaea15eb1711a7f,
  title = {Levels of stimulus control: a functional approach.},
  author = {R J Herrnstein},
  year = {1990},
  doi = {10.1016/0010-0277(90)90021-b},
  url = {https://pubmed.ncbi.nlm.nih.gov/2269005/},
  note = {Source identifier: 2269005}
}