@misc{indiciae7d50d213d8cf,
  title = {Black duck distribution, harvest characteristics, and survival},
  author = {Aelred D. Geis and Robert I. Smith and John P. Rogers},
  year = {1971},
  url = {https://pubs.usgs.gov/publication/ssrw139},
  note = {Source identifier: ssrw139}
}