@misc{indiciaedcb2e98d5ccf,
  title = {Two functional equations preserving functional forms.},
  author = {János Aczél and R Duncan Luce},
  year = {2002},
  doi = {10.1073/pnas.082107799},
  url = {https://pubmed.ncbi.nlm.nih.gov/16578868/},
  note = {Source identifier: 16578868}
}