MLA
Meek, Benjamin F. Letter from Benjamin K. Meek (Tuscaloosa, Alabama) to William E. Mickle (Mobile, Alabama) - August 26, 1892. 1892. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 9, Folder 17. https://digital.library.emory.edu/purl/4407wm38pv-cor.
APA, 6th edition
Meek, B. F. (1892). Letter from Benjamin K. Meek (Tuscaloosa, Alabama) to William E. Mickle (Mobile, Alabama) - August 26, 1892 (Box 9, Folder 17) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/4407wm38pv-cor.
Chicago
Meek, Benjamin F. “Letter from Benjamin K. Meek (Tuscaloosa, Alabama) to William E. Mickle (Mobile, Alabama) - August 26, 1892.” Letters (correspondence). Civil War Collection, 1892. Box 9, Folder 17. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/4407wm38pv-cor.