@misc{indiciaeb270f350e711,
  title = {Population ecology of the mallard: II. Breeding habitat conditions, size of the breeding populations, and production indices},
  author = {Richard S. Pospahala and David R. Anderson and Charles J. Henny},
  year = {1974},
  url = {https://pubs.usgs.gov/publication/rp115},
  note = {Source identifier: rp115}
}