MLA
Howard, Tazewell M. Letter from Tazewell M. Howard (Campbellton, Georgia) to His Brother, Dr. Thomas Henry Howard. Tazewell Howard Served as a Surgeon in the 55th Georgia Infantry Regiment - May 27, 1861. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 64. https://digital.library.emory.edu/purl/1741rn8qm5-cor.
APA, 6th edition
Howard, T. M. (1861). Letter from Tazewell M. Howard (Campbellton, Georgia) to his brother, Dr. Thomas Henry Howard. Tazewell Howard served as a surgeon in the 55th Georgia Infantry Regiment - May 27, 1861 (Box 3, Folder 64) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/1741rn8qm5-cor.
Chicago
Howard, Tazewell M. “Letter from Tazewell M. Howard (Campbellton, Georgia) to His Brother, Dr. Thomas Henry Howard. Tazewell Howard Served as a Surgeon in the 55th Georgia Infantry Regiment - May 27, 1861.” Letters (correspondence). Civil War Collection, 1861. Box 3, Folder 64. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/1741rn8qm5-cor.