@misc{indiciae03610c1275e7,
  title = {Geologic Map of the San Luis Hills Area, Conejos and Costilla Counties, Colorado},
  author = {Ren A. Thompson and Michael N. Machette},
  year = {1989},
  doi = {10.3133/i1906},
  url = {https://pubs.usgs.gov/publication/i1906},
  note = {Source identifier: i1906}
}