@misc{indiciae9e05030a2424,
  title = {Foveal increment thresholds in protan observers.},
  author = {R D Watkins},
  year = {1969},
  doi = {10.1016/0042-6989(69)90109-6},
  url = {https://pubmed.ncbi.nlm.nih.gov/5308024/},
  note = {Source identifier: 5308024}
}