@misc{indiciae3fa0f00bc9ce,
  title = {Effects of drugs on concurrent variable-interval variable-interval schedule performance.},
  author = {D E McMillan and M Li and S H Snodgrass},
  year = {1998},
  doi = {10.1097/00008877-199812000-00002},
  url = {https://pubmed.ncbi.nlm.nih.gov/9890256/},
  note = {Source identifier: 9890256}
}