MLA
Reynolds, Isaac Vermillion. Letter from Isaac Vermillion Reynolds (Rockingham County, Virginia) to His Wife. Reynolds Gives an Account of Movements during the Battle of Gettysburg. Reynolds Served in Company A of the 16th Virginia Cavalry Regiment - August 9, 1863 (Typescript). 1863. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 5, Folder 59. https://digital.library.emory.edu/purl/467jq2bwrq-cor.
APA, 6th edition
Reynolds, I. V. (1863). Letter from Isaac Vermillion Reynolds (Rockingham County, Virginia) to his wife. Reynolds gives an account of movements during the Battle of Gettysburg. Reynolds served in Company A of the 16th Virginia Cavalry Regiment - August 9, 1863 (typescript) (Box 5, Folder 59) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/467jq2bwrq-cor.
Chicago
Reynolds, Isaac Vermillion. “Letter from Isaac Vermillion Reynolds (Rockingham County, Virginia) to His Wife. Reynolds Gives an Account of Movements during the Battle of Gettysburg. Reynolds Served in Company A of the 16th Virginia Cavalry Regiment - August 9, 1863 (Typescript).” Letters (correspondence). Civil War Collection, 1863. Box 5, Folder 59. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/467jq2bwrq-cor.