@misc{indiciaec536ea611005,
  title = {Altitude, depth, and thickness of the Galena-Platteville Bedrock Unit in the subcrop area of Illinois and Wisconsin},
  author = {Timothy A. Brown and Charles P. Dunning and Jennifer B. Sharpe},
  year = {2000},
  doi = {10.3133/wri974054c},
  url = {https://pubs.usgs.gov/publication/wri974054C},
  note = {Source identifier: wri974054C}
}