@misc{indiciae734310468f00,
  title = {Exploration intensity map of the Upper Cretaceous Codell Sandstone, Denver basin, Colorado, Nebraska and Wyoming},
  author = {Debra K. Higley and D. L. Gautier and Richard F. Mast},
  year = {1987},
  doi = {10.3133/ofr87351e},
  url = {https://pubs.usgs.gov/publication/ofr87351E},
  note = {Source identifier: ofr87351E}
}