PDF fulltext* Bull, John L.; Farrand, John Jr.; Rayfield, Susan & National Audubon Society (1977): "The Audubon Society field guide to North American birds, Eastern Region".
PDF Volltext* Bull, John L.; Farrand, John Jr.; Rayfield, Susan & National Audubon Society (1977): "The Audubon Society field guide to North American birds, Eastern Region".