@misc{indiciaea94b0ccf9df1,
  title = {Mallard age and sex determination from wings},
  author = {S.M. Carney and A. D. Geis},
  year = {1960},
  doi = {10.2307/3796514},
  url = {https://pubs.usgs.gov/publication/5220751},
  note = {Source identifier: 5220751}
}