MLA
Clifton, William B. Letter from William B. Clifton (near Atlanta, Georgia) to His Brother-in-Law, Woodford Stone. The Letter Describes in Some Detail the Military Operations near Marietta and Atlanta - August 4, 1864 (Photocopy). 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 19, Folder 14. https://digital.library.emory.edu/purl/53976hdsdp-cor.
APA, 6th edition
Clifton, W. B. (1864). Letter from William B. Clifton (near Atlanta, Georgia) to his brother-in-law, Woodford Stone. The letter describes in some detail the military operations near Marietta and Atlanta - August 4, 1864 (photocopy) (Box 19, Folder 14) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/53976hdsdp-cor.
Chicago
Clifton, William B. “Letter from William B. Clifton (near Atlanta, Georgia) to His Brother-in-Law, Woodford Stone. The Letter Describes in Some Detail the Military Operations near Marietta and Atlanta - August 4, 1864 (Photocopy).” Letters (correspondence). Civil War Collection, 1864. Box 19, Folder 14. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/53976hdsdp-cor.