MLA
Jackson, Thomas Jonathan, 1824-1863. Letter from Thomas Jonathan "Stonewall" Jackson (near Mount Jackson, Virginia) to J. A. Harman - April 14, 1862. April 14, 1862. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/907tmpg5fp-cor.
APA, 6th edition
Jackson, Thomas Jonathan, 1824-1863. (April 14, 1862)[Letter from Thomas Jonathan "Stonewall" Jackson (near Mount Jackson, Virginia) to J. A. Harman - April 14, 1862]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/907tmpg5fp-cor.
Chicago
Jackson, Thomas Jonathan, 1824-1863, Letter from Thomas Jonathan "Stonewall" Jackson (near Mount Jackson, Virginia) to J. A. Harman - April 14, 1862, April 14, 1862, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/907tmpg5fp-cor.