@misc{indiciae01e335343716,
  title = {The overhead projector.},
  author = {N L Cole and W S Dougherty},
  year = {1971},
  doi = {10.1177/003693307101600106},
  url = {https://pubmed.ncbi.nlm.nih.gov/4105145/},
  note = {Source identifier: 4105145}
}