MLA
Jennings, Solomon. Letter from Solomon Jennings (Virginia) to His Father. Solomon Jennings Served in the 45th Virginia Infantry Regiment - March 16, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 4, Folder 8. https://digital.library.emory.edu/purl/825x69p9dh-cor.
APA, 6th edition
Jennings, S. (1862). Letter from Solomon Jennings (Virginia) to his father. Solomon Jennings served in the 45th Virginia Infantry Regiment - March 16, 1862 (Box 4, Folder 8) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/825x69p9dh-cor.
Chicago
Jennings, Solomon. “Letter from Solomon Jennings (Virginia) to His Father. Solomon Jennings Served in the 45th Virginia Infantry Regiment - March 16, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 4, Folder 8. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/825x69p9dh-cor.