MLA
Robinson, Carman A. Letter from Carman A. Robinson (Poughkeepsie, New York) to "Miss Southworth" (Memphis, Tennessee). Robinson, as a Union Soldier, Had Been Befriended by Miss Southworth during the War. He Asks Her to Help Him Find Employment in Memphis - January 13, 1866. 1866. Stuart A. Rose Manuscript, Archives, and Rare Book Library, Box 20, Folder 19. https://digital.library.emory.edu/purl/56341ns2zp-cor.
APA, 6th edition
Robinson, C. A. (1866). Letter from Carman A. Robinson (Poughkeepsie, New York) to "Miss Southworth" (Memphis, Tennessee). Robinson, as a Union soldier, had been befriended by Miss Southworth during the war. He asks her to help him find employment in Memphis - January 13, 1866 (Box 20, Folder 19) [Letters (correspondence)]. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/56341ns2zp-cor.
Chicago
Robinson, Carman A. “Letter from Carman A. Robinson (Poughkeepsie, New York) to ‘Miss Southworth’ (Memphis, Tennessee). Robinson, as a Union Soldier, Had Been Befriended by Miss Southworth during the War. He Asks Her to Help Him Find Employment in Memphis - January 13, 1866.” Letters (correspondence). Civil War Collection, 1866. Box 20, Folder 19. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/56341ns2zp-cor.