MLA
Letter from an Unknown Soldier (Charleston, South Carolina) to "Dear Elliot" - August 26, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 67. https://digital.library.emory.edu/purl/757np5hr26-cor.
APA, 6th edition
Letter from an unknown soldier (Charleston, South Carolina) to "Dear Elliot" - August 26, 1862 (Box 6, Folder 67). (1862). [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/757np5hr26-cor.
Chicago
“Letter from an Unknown Soldier (Charleston, South Carolina) to ‘Dear Elliot’ - August 26, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 6, Folder 67. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/757np5hr26-cor.