MLA
Riboud, David. Letter from David Riboud (Providence, Rhode Island) to His Grandmother, Vivian May Chase (Philadelphia, Pennsylvania) - September 24, 1984. 1984. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 1, Folder 9. https://digital.library.emory.edu/purl/7719kd527w-cor.
APA, 6th edition
Riboud, D. (1984). Letter from David Riboud (Providence, Rhode Island) to his grandmother, Vivian May Chase (Philadelphia, Pennsylvania) - September 24, 1984 (Box 1, Folder 9) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/7719kd527w-cor.
Chicago
Riboud, David. “Letter from David Riboud (Providence, Rhode Island) to His Grandmother, Vivian May Chase (Philadelphia, Pennsylvania) - September 24, 1984.” Letters (correspondence). Barbara Chase-Riboud Papers, 1984. Box 1, Folder 9. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/7719kd527w-cor.