MLA
Union Patriotic Envelope - Columbia Standing with a "Union" Object with Portrait of George Washington on It. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 7. https://digital.library.emory.edu/purl/788cfxpq31-cor.
APA, 6th edition
Union patriotic envelope - Columbia standing with a "Union" object with portrait of George Washington on it (Box 21, Folder 7). (1861). [Envelopes]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/788cfxpq31-cor.
Chicago
“Union Patriotic Envelope - Columbia Standing with a ‘Union’ Object with Portrait of George Washington on It.” Envelopes. Civil War Collection, 1861. Box 21, Folder 7. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/788cfxpq31-cor.