MLA
Union Patriotic Envelope - Cannon and United States Flag, "U[?]SA, 25-12.". 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 7. https://digital.library.emory.edu/purl/9289ghx4nh-cor.
APA, 6th edition
Union patriotic envelope - Cannon and United States flag, "U[?]SA, 25-12." (Box 21, Folder 7). (1861). [Envelopes]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/9289ghx4nh-cor.
Chicago
“Union Patriotic Envelope - Cannon and United States Flag, ‘U[?]SA, 25-12.".” Envelopes. Civil War Collection, 1861. Box 21, Folder 7. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/9289ghx4nh-cor.