APA

Fjeldsa J., .Color variation in the Ruddy Duck (<Oxyura jamaicensis andina>). : .

Chicago

Fjeldsa Jon, .Color variation in the Ruddy Duck (<Oxyura jamaicensis andina>). : .

Harvard

Fjeldsa J., .Color variation in the Ruddy Duck (<Oxyura jamaicensis andina>). : .

MLA

Fjeldsa Jon, .: . .