@misc{indiciae5d6cfb7e344d,
  title = {Slope maps: a new USGS product},
  author = {C.R. Gilman and F.S. Brownworth and C.W. Richter},
  year = {1975},
  doi = {10.3133/1677},
  url = {https://pubs.usgs.gov/publication/1677},
  note = {Source identifier: 1677}
}