MLA
Turner, H. H. Letter from H. H. Turner (Camp near Harpers Ferry, Virginia), Perhaps of the Pennsylvania Infantry, to "Dear Uncle and Friends��� - Turner Describes the Battle of Antietam, Which Occurred Nearby, and Camp Life in the Union Army - October 3, 1862 (Photocopy). 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 20, Folder 33. https://digital.library.emory.edu/purl/030prr4zp4-cor.
APA, 6th edition
Turner, H. H. (1862). Letter from H. H. Turner (Camp near Harpers Ferry, Virginia), perhaps of the Pennsylvania Infantry, to "Dear Uncle and Friends��� - Turner describes the battle of Antietam, which occurred nearby, and camp life in the Union Army - October 3, 1862 (photocopy) (Box 20, Folder 33) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/030prr4zp4-cor.
Chicago
Turner, H. H. “Letter from H. H. Turner (Camp near Harpers Ferry, Virginia), Perhaps of the Pennsylvania Infantry, to ‘Dear Uncle and Friends��� - Turner Describes the Battle of Antietam, Which Occurred Nearby, and Camp Life in the Union Army - October 3, 1862 (Photocopy).” Letters (correspondence). Civil War Collection, 1862. Box 20, Folder 33. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/030prr4zp4-cor.