MLA
Son, D. Murphy's. Union Patriotic Envelopes Dealing with Secession - "The Result of Secession" Published by D. Murphy's Sons. D. Murphy's Sons, Print, 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 8. https://digital.library.emory.edu/purl/0171vhhnnm-cor.
APA, 6th edition
Son, D. M. (1861). Union patriotic envelopes dealing with secession - "The Result of Secession" Published by D. Murphy's Sons (Box 21, Folder 8) [Envelopes]. D. Murphy's Sons, Print; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0171vhhnnm-cor.
Chicago
Son, D. Murphy's. “Union Patriotic Envelopes Dealing with Secession - ‘The Result of Secession’ Published by D. Murphy's Sons.” Envelopes. Civil War Collection. New York City, NY: D. Murphy's Sons, Print, 1861. Box 21, Folder 8. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0171vhhnnm-cor.