@misc{indiciae56287b49e05f,
  title = {ON DIFFERENTIAL SYSTEMS, II.},
  author = {V Guillemin and S Sternberg},
  year = {1963},
  doi = {10.1073/pnas.50.5.994},
  url = {https://pubmed.ncbi.nlm.nih.gov/16591130/},
  note = {Source identifier: 16591130}
}