MLA
Worthen, Appie. Letter from Appie Worthen (Barnesville, Georgia), to His Uncle - January 4, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 7, Folder 43. https://digital.library.emory.edu/purl/883xsj3w0n-cor.
APA, 6th edition
Worthen, A. (1864). Letter from Appie Worthen (Barnesville, Georgia), to his uncle - January 4, 1864 (Box 7, Folder 43) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/883xsj3w0n-cor.
Chicago
Worthen, Appie. “Letter from Appie Worthen (Barnesville, Georgia), to His Uncle - January 4, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 7, Folder 43. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/883xsj3w0n-cor.