@misc{indiciae60355a1d9342,
  title = {Rigidity: a function of reinforcement history.},
  author = {P M Bry and M M Nawas},
  year = {1969},
  doi = {10.2466/pms.1969.29.1.118},
  url = {https://pubmed.ncbi.nlm.nih.gov/5355022/},
  note = {Source identifier: 5355022}
}