MLA
Letter from an Unidentified Individual to "Mr. Blake" - June 7, 1865. 1865. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 1, Folder 31. https://digital.library.emory.edu/purl/119f4qrghf-cor.
APA, 6th edition
Letter from an unidentified individual to "Mr. Blake" - June 7, 1865 (Box 1, Folder 31). (1865). [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/119f4qrghf-cor.
Chicago
“Letter from an Unidentified Individual to ‘Mr. Blake’ - June 7, 1865.” Letters (correspondence). Civil War Collection, 1865. Box 1, Folder 31. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/119f4qrghf-cor.