MLA
Wesley, Sarah (Gwynne), 1726-1822. Letter from Sarah (Gwynne) Wesley to [Mrs.] Robert Thornton, Chesterfield Street, Marylebone, [London] - Febuary 21, 1803. February 21, 1803. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/4472v6wx6m-cor.
APA, 6th edition
Wesley, Sarah (Gwynne), 1726-1822. (February 21, 1803)[Letter from Sarah (Gwynne) Wesley to [Mrs.] Robert Thornton, Chesterfield Street, Marylebone, [London] - Febuary 21, 1803]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/4472v6wx6m-cor.
Chicago
Wesley, Sarah (Gwynne), 1726-1822, Letter from Sarah (Gwynne) Wesley to [Mrs.] Robert Thornton, Chesterfield Street, Marylebone, [London] - Febuary 21, 1803, February 21, 1803, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/4472v6wx6m-cor.