@misc{indiciaead76ccec74a4,
  title = {Invisible Sun-Spots.},
  author = {G E Hale},
  year = {1922},
  doi = {10.1073/pnas.8.7.168},
  url = {https://pubmed.ncbi.nlm.nih.gov/16586867/},
  note = {Source identifier: 16586867}
}