MLA
Wilson, Joseph. Letter from Joseph Wilson (Andersonville Prison, Georgia) to His Wife. He Writes of the Terrible Conditions and the Numerous Deaths in the Prison. Attached Is a Note Saying That Wilson Died in Andersonville and That a Clock Was to Be Raffled for the Benefit of His Wife and Children - July 21, 1864 (Photocopy). 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 20, Folder 40. https://digital.library.emory.edu/purl/0515mkkxkr-cor.
APA, 6th edition
Wilson, J. (1864). Letter from Joseph Wilson (Andersonville Prison, Georgia) to his wife. He writes of the terrible conditions and the numerous deaths in the prison. Attached is a note saying that Wilson died in Andersonville and that a clock was to be raffled for the benefit of his wife and children - July 21, 1864 (photocopy) (Box 20, Folder 40) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0515mkkxkr-cor.
Chicago
Wilson, Joseph. “Letter from Joseph Wilson (Andersonville Prison, Georgia) to His Wife. He Writes of the Terrible Conditions and the Numerous Deaths in the Prison. Attached Is a Note Saying That Wilson Died in Andersonville and That a Clock Was to Be Raffled for the Benefit of His Wife and Children - July 21, 1864 (Photocopy).” Letters (correspondence). Civil War Collection, 1864. Box 20, Folder 40. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/0515mkkxkr-cor.