@misc{indiciae4f2d2df3bf32,
  title = {Background and historical perspectives.},
  author = {C R Key},
  year = {1971},
  doi = {10.1016/s0046-8177(71)80048-5},
  url = {https://pubmed.ncbi.nlm.nih.gov/4939260/},
  note = {Source identifier: 4939260}
}