@misc{indiciaeb72a91472c88,
  title = {Union-Preserving Transformations of Differential-Elements.},
  author = {E Kasner and J De Cicco},
  year = {1943},
  doi = {10.1073/pnas.29.9.271},
  url = {https://pubmed.ncbi.nlm.nih.gov/16578089/},
  note = {Source identifier: 16578089}
}