MLA
Letter from Mary J. [Unidentified] (Charleston, South Carolina) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - November 18, [No Year]. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 6, Folder 55. https://digital.library.emory.edu/purl/2322bvq8sc-cor.
APA, 6th edition
Letter from Mary J. [unidentified] (Charleston, South Carolina) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - November 18, [no year] (Box 6, Folder 55). [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2322bvq8sc-cor.
Chicago
“Letter from Mary J. [Unidentified] (Charleston, South Carolina) to Cornelia E. Tillinghast (Gillisonville, South Carolina) - November 18, [No Year].” Letters (correspondence). Civil War Collection, n.d. Box 6, Folder 55. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/2322bvq8sc-cor.