@misc{indiciae22732792c6b3,
  title = {Contrast and spatial frequency.},
  author = {F W Campbell and L Maffei},
  year = {1974},
  doi = {10.1038/scientificamerican1174-106},
  url = {https://pubmed.ncbi.nlm.nih.gov/4432059/},
  note = {Source identifier: 4432059}
}