Mississippian Birdmen (Spotted Eagle and costumed human engraved coppers from Spiro and various Missouri sites).

Waring, A.J., Jr. 1940-1945. The Southern Cult and Muskogean Ceremonial. In The Waring Papers, The Collected Works of Antonio J. Waring, Jr., edited by Stephen Williams, p. 30-69. Peabody Museum of Archaeology and Ethnography, Cambridge MA. Fig. 14, P.14