@misc{indiciae4fab56509995,
  title = {Graded mental arithmetic as an active psychological challenge.},
  author = {J R Turner and J K Hewitt and R K Morgan and J Sims and D Carroll and K A Kelly},
  year = {1986},
  doi = {10.1016/0167-8760(86)90039-5},
  url = {https://pubmed.ncbi.nlm.nih.gov/3754545/},
  note = {Source identifier: 3754545}
}