MLA
Letter [Fragment] from an Unknown Soldier (Huguenot Springs, Virginia) to "Dear Mother" - August 13, 1863. 1863. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 73. https://digital.library.emory.edu/purl/054kkwh7q6-cor.
APA, 6th edition
Letter [fragment] from an unknown soldier (Huguenot Springs, Virginia) to "Dear mother" - August 13, 1863 (Box 6, Folder 73). (1863). [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/054kkwh7q6-cor.
Chicago
“Letter [Fragment] from an Unknown Soldier (Huguenot Springs, Virginia) to ‘Dear Mother’ - August 13, 1863.” Letters (correspondence). Civil War Collection, 1863. Box 6, Folder 73. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/054kkwh7q6-cor.