@misc{indiciaebea63fa521f7,
  title = {The Breeding Bird Survey, 1967 and 1968},
  author = {C.S. Robbins and W.T. Van Velzen},
  year = {1969},
  url = {https://pubs.usgs.gov/publication/5230026},
  note = {Source identifier: 5230026}
}