Udvardy, M. D. F. (1977). The Audubon Society field guide to North American birds--western region. Knopf : distributed by Random House.

Udvardy, Miklos D. F. The Audubon Society Field Guide to North American Birds--western Region. New York: Knopf : distributed by Random House, 1977.

Udvardy, Miklos D. F. The Audubon Society Field Guide to North American Birds--western Region. Knopf : distributed by Random House, 1977.