@misc{indiciae3ec464d28076,
  title = {AN ELECTIVE-PERIOD EXPERIMENT.},
  author = {A G WATKINS},
  year = {1964},
  doi = {10.1016/s0140-6736(64)90644-0},
  url = {https://pubmed.ncbi.nlm.nih.gov/14172367/},
  note = {Source identifier: 14172367}
}