MLA
Valentine, and Sons. The Trail in Front of the Beach Club, Palm Beach, Fla. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 71. https://digital.library.emory.edu/purl/170msbcc5k-cor.
APA, 6th edition
V., & S. The trail in front of the Beach Club, Palm Beach, Fla. (Box 71) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/170msbcc5k-cor.
Chicago
Valentine, and Sons. “The Trail in Front of the Beach Club, Palm Beach, 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/170msbcc5k-cor.