MLA
Murff, R. S. Letter from R. S. Murff (Camp of the 20th Mississippi Infantry Regiment, Grenada, Mississippi) to Reverend S. C. Johnson - February 25, 1865. 1865. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 34. https://digital.library.emory.edu/purl/317crjdgnh-cor.
APA, 6th edition
Murff, R. S. (1865). Letter from R. S. Murff (camp of the 20th Mississippi Infantry Regiment, Grenada, Mississippi) to Reverend S. C. Johnson - February 25, 1865 (Box 5, Folder 34) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/317crjdgnh-cor.
Chicago
Murff, R. S. “Letter from R. S. Murff (Camp of the 20th Mississippi Infantry Regiment, Grenada, Mississippi) to Reverend S. C. Johnson - February 25, 1865.” Letters (correspondence). Civil War Collection, 1865. Box 5, Folder 34. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/317crjdgnh-cor.