@misc{indiciae71696058be10,
  title = {Map showing bedrock topography beneath alluvial deposits of the Calhoun Quadrangle, western Kentucky},
  author = {A. E. Smith},
  year = {1975},
  doi = {10.3133/i906},
  url = {https://pubs.usgs.gov/publication/i906},
  note = {Source identifier: i906}
}