MLA
Mahone, William, 1826-1895. Letter from William Mahone (Virginia) to Henry B. Dawson, regarding his memoir. Mahone was a Confederate army veteran and later a United States Senator from Virginia - September 30, 1871. September 30, 1871. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/156zw3r354-cor.
APA, 6th edition
Mahone, William, 1826-1895. (September 30, 1871)[Letter from William Mahone (Virginia) to Henry B. Dawson, regarding his memoir. Mahone was a Confederate army veteran and later a United States Senator from Virginia - September 30, 1871]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/156zw3r354-cor.
Chicago
Mahone, William, 1826-1895, Letter from William Mahone (Virginia) to Henry B. Dawson, regarding his memoir. Mahone was a Confederate army veteran and later a United States Senator from Virginia - September 30, 1871, September 30, 1871, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/156zw3r354-cor.