MLA
Pickens, F. W. (Francis Wilkinson), 1805-1869. Letter from South Carolina Governor Francis Wilkinson Pickens to Confederate General Wilmot Gibbes DeSaussure - January 26, 1862. January 26, 1862. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0924b8gvgp-cor.
APA, 6th edition
Pickens, F. W. (Francis Wilkinson), 1805-1869. (January 26, 1862)[Letter from South Carolina Governor Francis Wilkinson Pickens to Confederate General Wilmot Gibbes DeSaussure - January 26, 1862]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0924b8gvgp-cor.
Chicago
Pickens, F. W. (Francis Wilkinson), 1805-1869, Letter from South Carolina Governor Francis Wilkinson Pickens to Confederate General Wilmot Gibbes DeSaussure - January 26, 1862, January 26, 1862, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0924b8gvgp-cor.