MLA
Johoske, Ercel B. (English). Letter from Ercel B. (English) Johoske (Clearwater, Florida) to professor Bell Wiley (Atlanta, Georgia) regarding Ercel sending her typescriped copy of her grandfather's diary to Emory University (photocopy). October 12, 1971. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrw53-cor.
APA, 6th edition
Johoske, Ercel B. (English). (October 12, 1971)[Letter from Ercel B. (English) Johoske (Clearwater, Florida) to professor Bell Wiley (Atlanta, Georgia) regarding Ercel sending her typescriped copy of her grandfather's diary to Emory University (photocopy)]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrw53-cor.
Chicago
Johoske, Ercel B. (English), Letter from Ercel B. (English) Johoske (Clearwater, Florida) to professor Bell Wiley (Atlanta, Georgia) regarding Ercel sending her typescriped copy of her grandfather's diary to Emory University (photocopy), October 12, 1971, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/081wdbrw53-cor.