@misc{indiciaeb631e0fbe495,
  title = {Results of spirit leveling in Minnesota, 1897 to 1914, inclusive},
  author = {Robert Bradford Marshall},
  year = {1915},
  doi = {10.3133/b560},
  url = {https://pubs.usgs.gov/publication/b560},
  note = {Source identifier: b560}
}