MLA
Godfrey, Ervin. Letter from Ervin Godfrey to His Wife. Godfrey Was a Doctor from Madison, Georgia - June 26, [No Year Provided]. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 37. https://digital.library.emory.edu/purl/003cz8wbj3-cor.
APA, 6th edition
Godfrey, E. Letter from Ervin Godfrey to his wife. Godfrey was a doctor from Madison, Georgia - June 26, [no year provided] (Box 3, Folder 37) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/003cz8wbj3-cor.
Chicago
Godfrey, Ervin. “Letter from Ervin Godfrey to His Wife. Godfrey Was a Doctor from Madison, Georgia - June 26, [No Year Provided].” Letters (correspondence). Civil War Collection, n.d. Box 3, Folder 37. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/003cz8wbj3-cor.