@misc{indiciaeac2749ed3a38,
  title = {The reinforcing effects of variable visual stimulation.},
  author = {J W Donahoe},
  year = {1965},
  doi = {10.1080/00221325.1965.10533660},
  url = {https://pubmed.ncbi.nlm.nih.gov/5852591/},
  note = {Source identifier: 5852591}
}