@misc{indiciaeefbff2600501,
  title = {Petroleum systems and assessment of undiscovered oil and gas in the Denver Basin Province, Colorado, Kansas, Nebraska, South Dakota, and Wyoming — USGS Province 39},
  author = {Debra K. Higley},
  year = {2007},
  doi = {10.3133/ds69p},
  url = {https://pubs.usgs.gov/publication/ds69P},
  note = {Source identifier: ds69P}
}