MLA
Groce, Lewis, Jr. Letter from Lewis Groce Jr. (near Manassas at Camp Bartow, Virginia), to His Sister. Groce, from Macon, Georgia, Served in Company A of the 20th Georgia Infantry Regiment - August 7, 1861 (Typescript). 1861. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 3, Folder 42. https://digital.library.emory.edu/purl/774qjq2cw0-cor.
APA, 6th edition
Groce, L., Jr. (1861). Letter from Lewis Groce Jr. (near Manassas at Camp Bartow, Virginia), to his sister. Groce, from Macon, Georgia, served in Company A of the 20th Georgia Infantry Regiment - August 7, 1861 (typescript) (Box 3, Folder 42) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/774qjq2cw0-cor.
Chicago
Groce, Lewis, Jr. “Letter from Lewis Groce Jr. (near Manassas at Camp Bartow, Virginia), to His Sister. Groce, from Macon, Georgia, Served in Company A of the 20th Georgia Infantry Regiment - August 7, 1861 (Typescript).” Letters (correspondence). Civil War Collection, 1861. Box 3, Folder 42. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/774qjq2cw0-cor.