@misc{indiciae5a12e28f6c0e,
  title = {Research problems and variables.},
  author = {R J Harmon and G A Morgan},
  year = {1999},
  doi = {10.1097/00004583-199906000-00029},
  url = {https://pubmed.ncbi.nlm.nih.gov/10361800/},
  note = {Source identifier: 10361800}
}