@misc{indiciaed987fdde1bae,
  title = {Preliminary geologic map of the Ekalaka 1° x 2° quadrangle, southeastern Montana and western North and South Dakota},
  author = {Roger B. Colton and S. T. Whitaker and W. C. Ehler and J. Holligan and C.G. Bowles},
  year = {1978},
  doi = {10.3133/ofr78493},
  url = {https://pubs.usgs.gov/publication/ofr78493},
  note = {Source identifier: ofr78493}
}