MLA
Bros., Robson. An Easton, MD, Watermelon Party. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 69. https://digital.library.emory.edu/purl/679573n5xv-cor.
APA, 6th edition
Bros., R. An Easton, MD, watermelon party (Box 69) [Photographic postcards]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/679573n5xv-cor.
Chicago
Bros., Robson. “An Easton, MD, Watermelon Party.” Photographic 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/679573n5xv-cor.