@misc{indiciaedc09979d0d05,
  title = {Oil shale of northwestern Colorado and northeastern Utah},
  author = {E. G. Woodruff and David T. Day},
  year = {1915},
  doi = {10.3133/b581a},
  url = {https://pubs.usgs.gov/publication/b581A},
  note = {Source identifier: b581A}
}