MLA
Spencer, Thomas. Stack of Cannonballs and Marker at the Site of the Headquarters of Union General William Rosecrans near Murfreesboro, Tennessee. 1940. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 15, Folder 7. https://digital.library.emory.edu/purl/825x69p9hp-cor.
APA, 6th edition
Spencer, T. (1940). Stack of cannonballs and marker at the site of the headquarters of Union general William Rosecrans near Murfreesboro, Tennessee (Box 15, Folder 7) [Black-and-white photographs]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/825x69p9hp-cor.
Chicago
Spencer, Thomas. “Stack of Cannonballs and Marker at the Site of the Headquarters of Union General William Rosecrans near Murfreesboro, Tennessee.” Black-and-white photographs. Civil War Collection, 1940. Box 15, Folder 7. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/825x69p9hp-cor.