Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood (2017) The eBird/Clements checklist of birds of the world: Version 2017 http://www.birds.cornell.edu/clementschecklist/download, läst 2017-08-11
doi.org
Pardieck, K. L.; Ziolkowski Jr., D. J.; Lutmerding, M.; Hudson, M. A. R. 2018. North American Breeding Bird Survey Dataset 1966 - 2017, version 2017.0. U.S. Geological Survey, Patuxent Wildlife Research Center Available at: https://doi.org/10.5066/F76972V8.