MLA
Herbert, Hilary A. (Hilary Abner), 1834-1919. Letter from Hilary Abner Herbert (Laurens, South Carolina) to General William E. Mickle, requesting a copy of the endorsement for his book - May 13, 1912. May 13, 1912. Civil War Collection. Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/1913n5tbsx-cor.
APA, 6th edition
Herbert, Hilary A. (Hilary Abner), 1834-1919. (May 13, 1912)[Letter from Hilary Abner Herbert (Laurens, South Carolina) to General William E. Mickle, requesting a copy of the endorsement for his book - May 13, 1912]. Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/1913n5tbsx-cor.
Chicago
Herbert, Hilary A. (Hilary Abner), 1834-1919, Letter from Hilary Abner Herbert (Laurens, South Carolina) to General William E. Mickle, requesting a copy of the endorsement for his book - May 13, 1912, May 13, 1912, Civil War Collection, Stuart A. Rose Manuscript, Archives, and Rare Book Library. https://digital.library.emory.edu/purl/1913n5tbsx-cor.