MLA
Edwards, W. W. Letter from W. W. Edwards (Leesburg, Virginia) to Mr. Thomas V. Humphris. Edwards Served in the 13th Mississippi Infantry Regiment - November 30, 1861. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 18. https://digital.library.emory.edu/purl/81289320fg-cor.
APA, 6th edition
Edwards, W. W. (1861). Letter from W. W. Edwards (Leesburg, Virginia) to Mr. Thomas V. Humphris. Edwards served in the 13th Mississippi Infantry Regiment - November 30, 1861 (Box 3, Folder 18) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/81289320fg-cor.
Chicago
Edwards, W. W. “Letter from W. W. Edwards (Leesburg, Virginia) to Mr. Thomas V. Humphris. Edwards Served in the 13th Mississippi Infantry Regiment - November 30, 1861.” Letters (correspondence). Civil War Collection, 1861. Box 3, Folder 18. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/81289320fg-cor.