@misc{indiciaea9777b6ddafe,
  title = {Black duck harvest and population dynamics in eastern Canada and the Atlantic Flyway},
  author = {R. K. Martinson and A. D. Geis and R.I. Smith},
  year = {1969},
  url = {https://pubs.usgs.gov/publication/5210049},
  note = {Source identifier: 5210049}
}