MLA
Jenkins, J. S. Letter from J. S. Jenkins to Susan A. Kenny. Jenkins Served in the 9th, Then 58th Alabama Infantry Regiment - July 8, 1864. 1864. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 4, Folder 28. https://digital.library.emory.edu/purl/836547d8z3-cor.
APA, 6th edition
Jenkins, J. S. (1864). Letter from J. S. Jenkins to Susan A. Kenny. Jenkins served in the 9th, then 58th Alabama Infantry Regiment - July 8, 1864 (Box 4, Folder 28) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/836547d8z3-cor.
Chicago
Jenkins, J. S. “Letter from J. S. Jenkins to Susan A. Kenny. Jenkins Served in the 9th, Then 58th Alabama Infantry Regiment - July 8, 1864.” Letters (correspondence). Civil War Collection, 1864. Box 4, Folder 28. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/836547d8z3-cor.