@misc{indiciae5bce58587547,
  title = {Perceptual activity and concept attainment.},
  author = {D Elkind and W van Doorninck and C Schwarz},
  year = {1967},
  url = {https://pubmed.ncbi.nlm.nih.gov/5583061/},
  note = {Source identifier: 5583061}
}