MLA
Longstreet, James, 1821-1904. Letter from Confederate General James Longstreet to Confederate General Robert E. Lee regarding military movements - October 28, 1863[?] (typescript). October 1863 approx.. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/460qrfj7r0-cor.
APA, 6th edition
Longstreet, James, 1821-1904. (October 1863 approx.)[Letter from Confederate General James Longstreet to Confederate General Robert E. Lee regarding military movements - October 28, 1863[?] (typescript)]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/460qrfj7r0-cor.
Chicago
Longstreet, James, 1821-1904, Letter from Confederate General James Longstreet to Confederate General Robert E. Lee regarding military movements - October 28, 1863[?] (typescript), October 1863 approx., Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/460qrfj7r0-cor.