@misc{indiciaef17cb47c4236,
  title = {On the intensity of the magnetic superstorm of September 1909},
  author = {Jeffrey J. Love and Hisashi Hayakawa and Edward W. Cliver},
  year = {2019},
  doi = {10.1029/2018sw002079},
  url = {https://pubs.usgs.gov/publication/70203248},
  note = {Source identifier: 70203248}
}