@misc{indiciae770ba168978f,
  title = {Problem solving in pre-operational youngsters.},
  author = {A G Zetlin},
  year = {1981},
  doi = {10.1111/j.1365-2788.1981.tb00100.x},
  url = {https://pubmed.ncbi.nlm.nih.gov/7265183/},
  note = {Source identifier: 7265183}
}