@misc{indiciaed157f2f1ddf8,
  title = {Proper retrospective study.},
  author = {G J Berdy and C W Roberts},
  year = {1989},
  doi = {10.1016/s0886-3350(89)80124-5},
  url = {https://pubmed.ncbi.nlm.nih.gov/2810101/},
  note = {Source identifier: 2810101}
}