MLA
Jewel, William. Letter from William Jewel (near Atlanta, Georgia) to His Sister - July 8, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 4, Folder 9. https://digital.library.emory.edu/purl/078gf1vjjj-cor.
APA, 6th edition
Jewel, W. (1864). Letter from William Jewel (near Atlanta, Georgia) to his sister - July 8, 1864 (Box 4, Folder 9) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/078gf1vjjj-cor.
Chicago
Jewel, William. “Letter from William Jewel (near Atlanta, Georgia) to His Sister - July 8, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 4, Folder 9. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/078gf1vjjj-cor.