@misc{indiciae5eb8063ae4ad,
  title = {A possible petroleum-related geochemical anomaly in surface rocks, Boulder and Weld counties, Colorado},
  author = {Terrence J. Donovan and Raymond L. Noble and Irving Friedman and Jim D. Gleason},
  year = {1975},
  doi = {10.3133/ofr7547},
  url = {https://pubs.usgs.gov/publication/ofr7547},
  note = {Source identifier: ofr7547}
}