@misc{indiciae400fa05fff3f,
  title = {Topographic instructions of the United States Geological Survey. Leveling},
  author = {E. M. Douglas},
  year = {1928},
  doi = {10.3133/b788d},
  url = {https://pubs.usgs.gov/publication/b788D},
  note = {Source identifier: b788D}
}