MLA
Chase-Riboud, Barbara. Letter from Barbara Chase-Riboud (Paris, France) to Her Stepfather, Ray - October 30, 1984. 1984. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 1, Folder 9. https://digital.library.emory.edu/purl/0859cnp6fz-cor.
APA, 6th edition
Chase-Riboud, B. (1984). Letter from Barbara Chase-Riboud (Paris, France) to her stepfather, Ray - October 30, 1984 (Box 1, Folder 9) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0859cnp6fz-cor.
Chicago
Chase-Riboud, Barbara. “Letter from Barbara Chase-Riboud (Paris, France) to Her Stepfather, Ray - October 30, 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/0859cnp6fz-cor.