MLA
Mayer, M. G. Stymie : an African American Boy with His Arm around a Dog. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 74. https://digital.library.emory.edu/purl/3655dv41qz-cor.
APA, 6th edition
Mayer, M. G. Stymie : an African American boy with his arm around a dog (Box 74) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3655dv41qz-cor.
Chicago
Mayer, M. G. “Stymie : an African American Boy with His Arm around a Dog.” Postcards. Robert Langmuir African American Photograph Collection, n.d. Box 74. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3655dv41qz-cor.