@misc{indiciae2cf1eeabf7af,
  title = {Focus difference in cue fading: a new technique.},
  author = {L E Acker},
  year = {1969},
  doi = {10.1901/jeab.1969.12-215},
  url = {https://pubmed.ncbi.nlm.nih.gov/16811346/},
  note = {Source identifier: 16811346}
}