MLA
Ficken, John F. Letter from John F. Ficken (Charleston, South Carolina) to James Simons, Regarding Returning Material to Him - December 3, 1906. 1905. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 8, Folder 26. https://digital.library.emory.edu/purl/689d51c61h-cor.
APA, 6th edition
Ficken, J. F. (1905). Letter from John F. Ficken (Charleston, South Carolina) to James Simons, regarding returning material to him - December 3, 1906 (Box 8, Folder 26) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/689d51c61h-cor.
Chicago
Ficken, John F. “Letter from John F. Ficken (Charleston, South Carolina) to James Simons, Regarding Returning Material to Him - December 3, 1906.” Letters (correspondence). Civil War Collection, 1905. Box 8, Folder 26. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/689d51c61h-cor.