MLA
Co., Detroit Publishing. Old City Gate, St. Augustine, Fla. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 71. https://digital.library.emory.edu/purl/962f7m0cmp-cor.
APA, 6th edition
Co., D. P. Old city gate, St. Augustine, Fla. (Box 71) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/962f7m0cmp-cor.
Chicago
Co., Detroit Publishing. “Old City Gate, St. Augustine, Fla.” Postcards. Robert Langmuir African American Photograph Collection, n.d. Box 71. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/962f7m0cmp-cor.