MLA
Co., E. C. Kropp. Greeting from Daytona, Fla. : Watermelon Days. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 69. https://digital.library.emory.edu/purl/426m0cfxtp-cor.
APA, 6th edition
Co., E. C. K. Greeting from Daytona, Fla. : watermelon days (Box 69) [Postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/426m0cfxtp-cor.
Chicago
Co., E. C. Kropp. “Greeting from Daytona, Fla. : Watermelon Days.” Postcards. Robert Langmuir African American Photograph Collection, n.d. Box 69. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/426m0cfxtp-cor.