MLA
Askew, Thomas E. Portrait of an African American Man in a Graduation Cap and Gown. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 18. https://digital.library.emory.edu/purl/907tmpg4rg-cor.
APA, 6th edition
Askew, T. E. Portrait of an African American man in a graduation cap and gown (Box 18) [Card photographs (photographs)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/907tmpg4rg-cor.
Chicago
Askew, Thomas E. “Portrait of an African American Man in a Graduation Cap and Gown.” Card photographs (photographs). Robert Langmuir African American Photograph Collection, n.d. Box 18. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/907tmpg4rg-cor.