MLA
Kavanaugh, H. H. (Hubbard Hinde), 1802-1884. Letter from H. H. Kavanaugh (Versaille, Kentucky) to Robert Paine - July 12, 1861. July 12, 1861. Robert Paine Papers, 1828-1882. Pitts Theology Library. https://digital.library.emory.edu/purl/491fj6q6d0-cor.
APA, 6th edition
Kavanaugh, H. H. (Hubbard Hinde), 1802-1884. (July 12, 1861)[Letter from H. H. Kavanaugh (Versaille, Kentucky) to Robert Paine - July 12, 1861]. Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/491fj6q6d0-cor.
Chicago
Kavanaugh, H. H. (Hubbard Hinde), 1802-1884, Letter from H. H. Kavanaugh (Versaille, Kentucky) to Robert Paine - July 12, 1861, July 12, 1861, Robert Paine Papers, 1828-1882, Pitts Theology Library. https://digital.library.emory.edu/purl/491fj6q6d0-cor.