MLA
Williams, James, 1796-1869. Letters on slavery from the old world : written during the canvass for the presidency of the United States in 1860 : to which are added a letter to Lord Brougham on the John Brown raid, and a brief reference to the result of the presidential contest and its consequences. 1861. Civil War Imprints. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6451g1k1kw-cor.
APA, 6th edition
Williams, James, 1796-1869. (1861)[Letters on slavery from the old world : written during the canvass for the presidency of the United States in 1860 : to which are added a letter to Lord Brougham on the John Brown raid, and a brief reference to the result of the presidential contest and its consequences]. Civil War Imprints, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6451g1k1kw-cor.
Chicago
Williams, James, 1796-1869, Letters on slavery from the old world : written during the canvass for the presidency of the United States in 1860 : to which are added a letter to Lord Brougham on the John Brown raid, and a brief reference to the result of the presidential contest and its consequences, 1861, Civil War Imprints, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/6451g1k1kw-cor.