@misc{indiciaed22d3cb8efc6,
  title = {The magnetic field in the United States, 1985: Horizontal intensity chart},
  author = {N.W. Peddie and A.K. Zunde},
  year = {1988},
  doi = {10.3133/gp986h},
  url = {https://pubs.usgs.gov/publication/gp986H},
  note = {Source identifier: gp986H}
}