MLA
Reynolds, John C. Letter from John C. Reynolds (Confederate States of America Engineers Office, Macon, Georgia) to John H. Glenn (Macon, Georgia) - January 21, 1865. 1865. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 60. https://digital.library.emory.edu/purl/344pk0p3pk-cor.
APA, 6th edition
Reynolds, J. C. (1865). Letter from John C. Reynolds (Confederate States of America Engineers Office, Macon, Georgia) to John H. Glenn (Macon, Georgia) - January 21, 1865 (Box 5, Folder 60) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/344pk0p3pk-cor.
Chicago
Reynolds, John C. “Letter from John C. Reynolds (Confederate States of America Engineers Office, Macon, Georgia) to John H. Glenn (Macon, Georgia) - January 21, 1865.” Letters (correspondence). Civil War Collection, 1865. Box 5, Folder 60. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/344pk0p3pk-cor.