MLA
Ward, Joseph W. Letter from Joseph W. Ward (Camp near Fernandina, Florida) to His Father. Ward Was an Officer in Company L of the 24th Mississippi Infantry - January 25, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 7, Folder 12. https://digital.library.emory.edu/purl/39995x6brs-cor.
APA, 6th edition
Ward, J. W. (1862). Letter from Joseph W. Ward (Camp near Fernandina, Florida) to his father. Ward was an officer in Company L of the 24th Mississippi Infantry - January 25, 1862 (Box 7, Folder 12) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/39995x6brs-cor.
Chicago
Ward, Joseph W. “Letter from Joseph W. Ward (Camp near Fernandina, Florida) to His Father. Ward Was an Officer in Company L of the 24th Mississippi Infantry - January 25, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 7, Folder 12. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/39995x6brs-cor.