@misc{indiciae90a61b4540c1,
  title = {Durable secondary reinforcement: method and theory.},
  author = {D W ZIMMERMAN},
  year = {1957},
  doi = {10.1037/h0041885},
  url = {https://pubmed.ncbi.nlm.nih.gov/13505973/},
  note = {Source identifier: 13505973}
}