MLA
Union Patriotic Envelopes - "Oh Dear! Dear! This Is a Much Heavier Burden than I Had Ever Anticipated!!". 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 9. https://digital.library.emory.edu/purl/7956djhc30-cor.
APA, 6th edition
Union patriotic envelopes - "Oh Dear! Dear! This is a much heavier burden than I had ever anticipated!!" (Box 21, Folder 9). (1861). [Envelopes]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/7956djhc30-cor.
Chicago
“Union Patriotic Envelopes - ‘Oh Dear! Dear! This Is a Much Heavier Burden than I Had Ever Anticipated!!".” Envelopes. Civil War Collection, 1861. Box 21, Folder 9. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/7956djhc30-cor.