@misc{indiciaece8b5e0dd974,
  title = {Generalization gradients and stimulus control in delayed matching-to-sample.},
  author = {M Sidman},
  year = {1969},
  doi = {10.1901/jeab.1969.12-745},
  url = {https://pubmed.ncbi.nlm.nih.gov/5359623/},
  note = {Source identifier: 5359623}
}