@misc{indiciae26015df088d1,
  title = {The magnetic field in the United States, 1985: Total intensity chart},
  author = {N.W. Peddie and A.K. Zunde},
  year = {1988},
  doi = {10.3133/gp986f},
  url = {https://pubs.usgs.gov/publication/gp986F},
  note = {Source identifier: gp986F}
}