@misc{indiciae39a3d1c73d1e,
  title = {Variable-time reinforcement in multiple and concurrent schedules.},
  author = {D M Wilkie},
  year = {1972},
  doi = {10.1901/jeab.1972.17-59},
  url = {https://pubmed.ncbi.nlm.nih.gov/16811568/},
  note = {Source identifier: 16811568}
}