@misc{indiciae99f9c76b0db9,
  title = {Geology of the conterminous United States at 1:2,500,000 scale a digital representation of the 1974 P.B. King and H.M. Beikman map},
  author = {Paul G. Schruben and Raymond E. Arndt and Walter J. Bawiec},
  year = {1998},
  doi = {10.3133/ds11},
  url = {https://pubs.usgs.gov/publication/ds11},
  note = {Source identifier: ds11}
}