MLA
Roach, James L. Letter from James L. Roach (High Shoals, Georgia) to "Dear Doctor" - September 3, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 1. https://digital.library.emory.edu/purl/276f1vhj9c-cor.
APA, 6th edition
Roach, J. L. (1864). Letter from James L. Roach (High Shoals, Georgia) to "Dear Doctor" - September 3, 1864 (Box 6, Folder 1) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/276f1vhj9c-cor.
Chicago
Roach, James L. “Letter from James L. Roach (High Shoals, Georgia) to ‘Dear Doctor’ - September 3, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 6, Folder 1. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/276f1vhj9c-cor.