@misc{indiciaea17580113427,
  title = {Non-Separable and Planar Graphs.},
  author = {H Whitney},
  year = {1931},
  doi = {10.1073/pnas.17.2.125},
  url = {https://pubmed.ncbi.nlm.nih.gov/16587624/},
  note = {Source identifier: 16587624}
}