@misc{indiciaea92a7db7a8e6,
  title = {The magnetic field in the United States, 1985: Declination chart},
  author = {N.W. Peddie and A.K. Zunde},
  year = {1988},
  doi = {10.3133/gp986d},
  url = {https://pubs.usgs.gov/publication/gp986D},
  note = {Source identifier: gp986D}
}