1. Surf Scoter (Melanitta perspicillata), version 2.0;Anderson,2015
2. Lesser Scaup (Aythya affinis), version 2.0;Anteau,2014
3. Biological exhuberance: Animal homosexuality and natural diversity;Bagemihl,1999
4. Waterfowl ecology and management;Baldassarre,2006
5. Hawaiian Goose (Branta sandvicensis), version 2.0;Banko,1999