Robert Braun. Identifying Audubon Bird Prints. Originals, States, Editions, Restrikes, and Facsimiles and Reproductions.
Fairfield, Connecticut, 2001. Paper.
An extremely useful identification guide to all Audubon bird prints. Separately issued reprint of an article which appeared in Imprint V. 21 #2 (1996), with new color illustrations and updated bibliography.