MLA
Stevens, G. W. A Large Stage, Where the Alabama Troubadours Are Performing. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 70. https://digital.library.emory.edu/purl/5977sqv9xc-cor.
APA, 6th edition
Stevens, G. W. A large stage, where the Alabama Troubadours are performing (Box 70) [Photographic postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/5977sqv9xc-cor.
Chicago
Stevens, G. W. “A Large Stage, Where the Alabama Troubadours Are Performing.” Photographic postcards. Robert Langmuir African American Photograph Collection, n.d. Box 70. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/5977sqv9xc-cor.