@misc{indiciaea29a7932836e,
  title = {On Homotopy Groups.},
  author = {S Eilenberg},
  year = {1940},
  doi = {10.1073/pnas.26.9.563},
  url = {https://pubmed.ncbi.nlm.nih.gov/16588404/},
  note = {Source identifier: 16588404}
}