MLA
Wesley, John, 1703-1791. Letter from John Wesley to "Peggy" Margaret (Dale) Avison, Witney - August 27, 1767. August 27, 1767. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/969866t226-cor.
APA, 6th edition
Wesley, John, 1703-1791. (August 27, 1767)[Letter from John Wesley to "Peggy" Margaret (Dale) Avison, Witney - August 27, 1767]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/969866t226-cor.
Chicago
Wesley, John, 1703-1791, Letter from John Wesley to "Peggy" Margaret (Dale) Avison, Witney - August 27, 1767, August 27, 1767, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/969866t226-cor.