MLA
Dorsey, John M. Letter from John M. Dorsey[?] to "Dear Sister," (Brown County, Mississippi[?]) - June 18, 1867 (Typescript). 1867. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 8. https://digital.library.emory.edu/purl/218dfn305x-cor.
APA, 6th edition
Dorsey, J. M. (1867). Letter from John M. Dorsey[?] to "Dear Sister," (Brown County, Mississippi[?]) - June 18, 1867 (typescript) (Box 3, Folder 8) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/218dfn305x-cor.
Chicago
Dorsey, John M. “Letter from John M. Dorsey[?] to ‘Dear Sister," (Brown County, Mississippi[?]) - June 18, 1867 (Typescript).” Letters (correspondence). Civil War Collection, 1867. Box 3, Folder 8. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/218dfn305x-cor.