MLA
Thornton, Samuel S. Letter from Thornton (Camp Buckner, Talladega, Alabama) to "Dear Cousin" - July 10, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 52. https://digital.library.emory.edu/purl/8708w9gjnp-cor.
APA, 6th edition
Thornton, S. S. (1864). Letter from Thornton (Camp Buckner, Talladega, Alabama) to "Dear Cousin" - July 10, 1864 (Box 6, Folder 52) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/8708w9gjnp-cor.
Chicago
Thornton, Samuel S. “Letter from Thornton (Camp Buckner, Talladega, Alabama) to ‘Dear Cousin’ - July 10, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 6, Folder 52. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/8708w9gjnp-cor.