MLA
McConnoly[?], M. Letter to Mr. Blake (Pocotaligo, [S.C.]) from M. McConoly[?] - January, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 1, Folder 31. https://digital.library.emory.edu/purl/078gf1vjj1-cor.
APA, 6th edition
McConnoly[?], M. (1864). Letter to Mr. Blake (Pocotaligo, [S.C.]) from M. McConoly[?] - January, 1864 (Box 1, Folder 31) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/078gf1vjj1-cor.
Chicago
McConnoly[?], M. “Letter to Mr. Blake (Pocotaligo, [S.C.]) from M. McConoly[?] - January, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 1, Folder 31. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/078gf1vjj1-cor.