MLA
Union Patriotic Envelope - "[Fort] Sumter, Union Forever". 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 7. https://digital.library.emory.edu/purl/156zw3r388-cor.
APA, 6th edition
Union patriotic envelope - "[Fort] Sumter, Union Forever" (Box 21, Folder 7). (1861). [Envelopes]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/156zw3r388-cor.
Chicago
“Union Patriotic Envelope - "[Fort] Sumter, Union Forever.’” Envelopes. Civil War Collection, 1861. Box 21, Folder 7. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/156zw3r388-cor.