MLA
Gorgas, Josiah, 1818-1883. Letter from Josiah Gorgas (Richmond, Virginia) to John Letcher, requesting artillery pieces - August 11, 1861. August 11, 1861. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3483j9kf5d-cor.
APA, 6th edition
Gorgas, Josiah, 1818-1883. (August 11, 1861)[Letter from Josiah Gorgas (Richmond, Virginia) to John Letcher, requesting artillery pieces - August 11, 1861]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3483j9kf5d-cor.
Chicago
Gorgas, Josiah, 1818-1883, Letter from Josiah Gorgas (Richmond, Virginia) to John Letcher, requesting artillery pieces - August 11, 1861, August 11, 1861, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/3483j9kf5d-cor.