@misc{indiciae558a92350d61,
  title = {Color shaded relief map of the conterminous United States},
  author = {P. G. Schruben},
  year = {1999},
  doi = {10.3133/ofr9911},
  url = {https://pubs.usgs.gov/publication/ofr9911},
  note = {Source identifier: ofr9911}
}