MLA
Early, John, 1786-1873. Letter from John Early (Near Richmond, Virginia) to Robert Paine - July 19, 1871. July 19, 1871. Robert Paine Papers, 1828-1882. Pitts Theology Library. https://digital.library.emory.edu/purl/453wstqkt7-cor.
APA, 6th edition
Early, John, 1786-1873. (July 19, 1871)[Letter from John Early (Near Richmond, Virginia) to Robert Paine - July 19, 1871]. Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/453wstqkt7-cor.
Chicago
Early, John, 1786-1873, Letter from John Early (Near Richmond, Virginia) to Robert Paine - July 19, 1871, July 19, 1871, Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/453wstqkt7-cor.