@misc{indiciae7b8bb7ea37a5,
  title = {A description of colored gravity and terrain maps for the United States and adjacent Canada east of 104 degrees},
  author = {R.W. Simpson and T.G. Hildenbrand and R. H. Godson and M. F. Kane},
  year = {1982},
  doi = {10.3133/ofr82877},
  url = {https://pubs.usgs.gov/publication/ofr82877},
  note = {Source identifier: ofr82877}
}