@misc{indiciae93288d0171e5,
  title = {Geothermal energy: clean power from the Earth's heat},
  author = {Wendell A. Duffield and John H. Sass},
  year = {2003},
  doi = {10.3133/cir1249},
  url = {https://pubs.usgs.gov/publication/cir1249},
  note = {Source identifier: cir1249}
}