MLA
Frank Hart, Center, with Englehardt, Left, and O'Leary, Right. 1874. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 63. https://digital.library.emory.edu/purl/2902z34tqr-cor.
APA, 6th edition
Frank Hart, center, with Englehardt, left, and O'Leary, right (Box 63). (1874). [Card photographs (photographs)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2902z34tqr-cor.
Chicago
“Frank Hart, Center, with Englehardt, Left, and O'Leary, Right.” Card photographs (photographs). Robert Langmuir African American Photograph Collection, 1874. Box 63. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2902z34tqr-cor.