MLA
Doyle, Roy. Martin Luther King in a Scene at the Famous Mammoth Cave Wax Museum, Cave City, Kentucky. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 74. https://digital.library.emory.edu/purl/385n8pk0rn-cor.
APA, 6th edition
Doyle, R. Martin Luther King in a scene at the famous Mammoth Cave Wax Museum, Cave City, Kentucky (Box 74) [Photographic postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/385n8pk0rn-cor.
Chicago
Doyle, Roy. “Martin Luther King in a Scene at the Famous Mammoth Cave Wax Museum, Cave City, Kentucky.” Photographic postcards. Robert Langmuir African American Photograph Collection, n.d. Box 74. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/385n8pk0rn-cor.