Cygnus olor (Mute Swan)
- Species account includes facts on geographic range, physical traits, and behavior. Provides photos.
- http://animaldiversity.ummz.umich.edu/site/accounts/information/Cygnus_olor.html

Cygnus buccinator (Trumpeter Swan)
- Photos, taxonomy, reproduction, habitat, food habits, and conservation status.
- http://animaldiversity.ummz.umich.edu/site/accounts/information/Cygnus_buccinator.html

The Trumpeter Swan Society
- A private, non-profit organization dedicated to assuring the vitality and welfare of wild Trumpeter Swan populations.
- http://www.trumpeterswansociety.org/

Mute Swan (Cygnus olor)
- Provides an image, range maps, and facts about this bird's diet, habitat, and physical characteristics.
- http://www.nenature.com/MuteSwan.htm

Mute Swan (Cygnus olor)
- Facts about the history, nesting, and diet of this introduced New Zealand bird.
- http://nzbirds.com/Muteswan.html

Whooper Swan (Cygnus cygnus)
- Photos and tips on distinguishing this bird from the Mute Swan. Includes data on distribution in Iceland, Europe, and Asia.
- http://www.arthurgrosset.com/europebirds/whooperswan.html

Bewick's Swan
- Short article on Cygnus columbianus in Britain.
- http://www.birdsofbritain.co.uk/bird-guide/bewick-swan.htm

Did Trumpeter Swans Ever Breed in Eastern North America?
- Discussion by Bill Whan and Gerry Rising of the controversial program for introduction of Cygnus buccinator into the eastern US.
- http://www.acsu.buffalo.edu/~insrisg/nature/swans.html

Trumpeter Swan (Olor buccinator)
- Describes the behavior, conservation status, risk factors, and outlook for this species.
- http://raysweb.net/specialplaces/pages/swan.html