@misc{indiciae18f419a57d03,
  title = {A description of colored gravity and terrain maps for the conterminous United States, shown on 35-mm slides},
  author = {R.W. Simpson and T.H. Hildenbrand and R. H. Godson and M. F. Kane},
  year = {1982},
  doi = {10.3133/ofr82477},
  url = {https://pubs.usgs.gov/publication/ofr82477},
  note = {Source identifier: ofr82477}
}