@misc{indiciaebfb31e20abba,
  title = {Total-count gamma radiation map of the Bopolu Quadrangle, Liberia},
  author = {John C. Behrendt and C.S. Wotorson},
  year = {1974},
  doi = {10.3133/i772c},
  url = {https://pubs.usgs.gov/publication/i772C},
  note = {Source identifier: i772C}
}