MLA
Murphy, Anthony. Letter from Anthony Murphy to D. A. Dorsey about Andrew's Raid (April 4, 1862) - December 5, 1891 (Typescript). 1891. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 8, Folder 3. https://digital.library.emory.edu/purl/293gxd25t1-cor.
APA, 6th edition
Murphy, A. (1891). Letter from Anthony Murphy to D. A. Dorsey about Andrew's Raid (April 4, 1862) - December 5, 1891 (typescript) (Box 8, Folder 3) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/293gxd25t1-cor.
Chicago
Murphy, Anthony. “Letter from Anthony Murphy to D. A. Dorsey about Andrew's Raid (April 4, 1862) - December 5, 1891 (Typescript).” Letters (correspondence). Civil War Collection, 1891. Box 8, Folder 3. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/293gxd25t1-cor.