@misc{indiciae76d49a42ba3b,
  title = {Map Showing Construction Materials and Nonmetallic Mineral Resources of South Dakota},
  author = {Robert P. Bryson and E.C. Fischer and E.L. Fox and D. M. Larrabee and R. A. Weeks},
  year = {1947},
  doi = {10.3133/mb12},
  url = {https://pubs.usgs.gov/publication/mb12},
  note = {Source identifier: mb12}
}