@misc{indiciae11492595c9b3,
  title = {On regional geomagnetic charts},
  author = {L.R. Alldredge},
  year = {1987},
  doi = {10.5636/jgg.39.723},
  url = {https://pubs.usgs.gov/publication/70014158},
  note = {Source identifier: 70014158}
}