MLA
Johnson, D. G. Letter from D. G. Johnson (Crossroads New Kent County, Virginia) to "Dear Ella and Pa." Johnson Served in Cobb's Brigade, 15th North Carolina Infantry Regiment - May 12, 1862. 1862. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 4, Folder 13. https://digital.library.emory.edu/purl/484mkkwj6m-cor.
APA, 6th edition
Johnson, D. G. (1862). Letter from D. G. Johnson (Crossroads New Kent County, Virginia) to "Dear Ella and Pa." Johnson served in Cobb's Brigade, 15th North Carolina Infantry Regiment - May 12, 1862 (Box 4, Folder 13) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/484mkkwj6m-cor.
Chicago
Johnson, D. G. “Letter from D. G. Johnson (Crossroads New Kent County, Virginia) to ‘Dear Ella and Pa." Johnson Served in Cobb's Brigade, 15th North Carolina Infantry Regiment - May 12, 1862.” Letters (correspondence). Civil War Collection, 1862. Box 4, Folder 13. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/484mkkwj6m-cor.