MLA
Alexander, Edward Porter, 1835-1910. Letter from Edward Porter Alexander (New York City, New York) to James Longstreet - December 17, 1887 (typescript). December 17, 1887. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/955m905rhp-cor.
APA, 6th edition
Alexander, Edward Porter, 1835-1910. (December 17, 1887)[Letter from Edward Porter Alexander (New York City, New York) to James Longstreet - December 17, 1887 (typescript)]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/955m905rhp-cor.
Chicago
Alexander, Edward Porter, 1835-1910, Letter from Edward Porter Alexander (New York City, New York) to James Longstreet - December 17, 1887 (typescript), December 17, 1887, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/955m905rhp-cor.