@misc{indiciae24cd106ddb44,
  title = {General Projective Differential Geometry.},
  author = {A D Michal},
  year = {1937},
  doi = {10.1073/pnas.23.10.546},
  url = {https://pubmed.ncbi.nlm.nih.gov/16577813/},
  note = {Source identifier: 16577813}
}