MLA
Magee, John L. Union Patriotic Envelopes Dealing with Secession - "Old Blowregard Will Soon Expire, While Thus He Drills His Shy Man-Asses, For They Can Never Stand Our Fire, While They Feed on Secession Grasses." Published by John L. Magee, Philadelphia, Pennsylvania. Magee, John L., 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 21, Folder 8. https://digital.library.emory.edu/purl/3246q574tr-cor.
APA, 6th edition
Magee, J. L. (1861). Union patriotic envelopes dealing with secession - "Old Blowregard will soon expire, While thus he drills his shy man-asses, For they can never stand our fire, While they feed on Secession grasses." Published by John L. Magee, Philadelphia, Pennsylvania (Box 21, Folder 8) [Envelopes]. Magee, John L.; Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3246q574tr-cor.
Chicago
Magee, John L. “Union Patriotic Envelopes Dealing with Secession - ‘Old Blowregard Will Soon Expire, While Thus He Drills His Shy Man-Asses, For They Can Never Stand Our Fire, While They Feed on Secession Grasses." Published by John L. Magee, Philadelphia, Pennsylvania.” Envelopes. Civil War Collection. Philadelphia, PA: Magee, John L., 1861. Box 21, Folder 8. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3246q574tr-cor.