@misc{indiciaec68515bdaa8e,
  title = {Composite magnetic anomaly map of the conterminous United States west of 96° longitude},
  author = {K. R. Bond and Isidore Zietz},
  year = {1987},
  doi = {10.3133/gp977},
  url = {https://pubs.usgs.gov/publication/gp977},
  note = {Source identifier: gp977}
}