MLA
Pierce, George F. (George Foster), 1811-1884. Letter from George F. Pierce (Culverton, Georgia) to Robert Paine (Aberdeen, Mississippi) - May 29, 1861. May 29, 1861. Robert Paine Papers, 1828-1882. Pitts Theology Library. https://digital.library.emory.edu/purl/27312jm78k-cor.
APA, 6th edition
Pierce, George F. (George Foster), 1811-1884. (May 29, 1861)[Letter from George F. Pierce (Culverton, Georgia) to Robert Paine (Aberdeen, Mississippi) - May 29, 1861]. Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/27312jm78k-cor.
Chicago
Pierce, George F. (George Foster), 1811-1884, Letter from George F. Pierce (Culverton, Georgia) to Robert Paine (Aberdeen, Mississippi) - May 29, 1861, May 29, 1861, Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/27312jm78k-cor.