MLA
Martin, R. O. Portrait of Mattie Martin. 1880. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 62. https://digital.library.emory.edu/purl/682k6djhdm-cor.
APA, 6th edition
Martin, R. O. (1880). Portrait of Mattie Martin (Box 62) [Card photographs (photographs)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/682k6djhdm-cor.
Chicago
Martin, R. O. “Portrait of Mattie Martin.” Card photographs (photographs). Robert Langmuir African American Photograph Collection, 1880. Box 62. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/682k6djhdm-cor.