@misc{indiciae7cb3ceb57990,
  title = {Transcontinental geophysical survey (35° - 39° N) geologic map from 87° to 100° W longitude},
  author = {Ronald Willden and J. E. Carlson},
  year = {1968},
  doi = {10.3133/i534c},
  url = {https://pubs.usgs.gov/publication/i534C},
  note = {Source identifier: i534C}
}