@misc{indiciae9b69e010b8cc,
  title = {Spirit leveling in Illinois, 1914 to 1917, inclusive},
  author = {Robert Bradford Marshall},
  year = {1918},
  doi = {10.3133/b672},
  url = {https://pubs.usgs.gov/publication/b672},
  note = {Source identifier: b672}
}