MLA
Arewood, Gilbrite. Letter from Gilbrite Arewood (Camp Mangum, Raleigh, North Carolina) to His Wife, Amanda Arewood - December 22, 1861. 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 1, Folder 8. https://digital.library.emory.edu/purl/969866t2k2-cor.
APA, 6th edition
Arewood, G. (1861). Letter from Gilbrite Arewood (Camp Mangum, Raleigh, North Carolina) to his wife, Amanda Arewood - December 22, 1861 (Box 1, Folder 8) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/969866t2k2-cor.
Chicago
Arewood, Gilbrite. “Letter from Gilbrite Arewood (Camp Mangum, Raleigh, North Carolina) to His Wife, Amanda Arewood - December 22, 1861.” Letters (correspondence). Civil War Collection, 1861. Box 1, Folder 8. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/969866t2k2-cor.