MLA
Wesley, Sarah (Gwynne), 1726-1822. Letter from Sarah (Gwynne) Wesley to William Wilberforce, Buckingham Place [London] - September 5, 1814. September 5, 1814. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/470zpc86s1-cor.
APA, 6th edition
Wesley, Sarah (Gwynne), 1726-1822. (September 5, 1814)[Letter from Sarah (Gwynne) Wesley to William Wilberforce, Buckingham Place [London] - September 5, 1814]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/470zpc86s1-cor.
Chicago
Wesley, Sarah (Gwynne), 1726-1822, Letter from Sarah (Gwynne) Wesley to William Wilberforce, Buckingham Place [London] - September 5, 1814, September 5, 1814, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/470zpc86s1-cor.