@misc{indiciae43d65c49bbd8,
  title = {Reading aids for the partially sighted. A nontechnical explanation of basic optical principles.},
  author = {L L Sloan and S J Ryan},
  year = {1971},
  url = {https://pubmed.ncbi.nlm.nih.gov/5129706/},
  note = {Source identifier: 5129706}
}