MLA
Alexander, Edward Porter, 1835-1910. Letter from Edward P. Alexander (Columbia, South Carolina) to George Pickett - June 16, 1866 (typescript). June 16, 1866. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bm2v-cor.
APA, 6th edition
Alexander, Edward Porter, 1835-1910. (June 16, 1866)[Letter from Edward P. Alexander (Columbia, South Carolina) to George Pickett - June 16, 1866 (typescript)]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bm2v-cor.
Chicago
Alexander, Edward Porter, 1835-1910, Letter from Edward P. Alexander (Columbia, South Carolina) to George Pickett - June 16, 1866 (typescript), June 16, 1866, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/245q83bm2v-cor.