@misc{indiciae5980e87c391b,
  title = {Experimental digital shaded-relief maps of southwestern United States},
  author = {Kathleen Edwards and R. M. Batson},
  year = {1990},
  doi = {10.3133/i1850},
  url = {https://pubs.usgs.gov/publication/i1850},
  note = {Source identifier: i1850}
}