MLA
Letter from Robert N. Waggoner, Department of the Army, Historical Services Division, to Nena Perry, Emory University School of Medicine, Regarding Obtaining Copies of Official Documents of the 43rd General Hospital Unit for Use in a Published Work - August 17, 1981. 1981. Robert W. Woodruff Health Sciences Center. Library, Box 1, Folder 9. https://digital.library.emory.edu/purl/948sbcc3t2-cor.
APA, 6th edition
Letter from Robert N. Waggoner, Department of the Army, Historical Services Division, to Nena Perry, Emory University School of Medicine, regarding obtaining copies of official documents of the 43rd General Hospital unit for use in a published work - August 17, 1981 (Box 1, Folder 9). (1981). [Letters (correspondence)]. Robert W. Woodruff Health Sciences Center. Library. https://digital.library.emory.edu/purl/948sbcc3t2-cor.
Chicago
“Letter from Robert N. Waggoner, Department of the Army, Historical Services Division, to Nena Perry, Emory University School of Medicine, Regarding Obtaining Copies of Official Documents of the 43rd General Hospital Unit for Use in a Published Work - August 17, 1981.” Letters (correspondence). Emory Unit Collection, 1981. Box 1, Folder 9. Robert W. Woodruff Health Sciences Center. Library. https://digital.library.emory.edu/purl/948sbcc3t2-cor.