MLA
Wesley, Samuel, 1766-1837. Letter from Samuel Wesley to George Augustus Polgreen Bridgetower, Gower Place, Euston Square [London] - September 22, 1815. September 22, 1815. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/160cvdnd2v-cor.
APA, 6th edition
Wesley, Samuel, 1766-1837. (September 22, 1815)[Letter from Samuel Wesley to George Augustus Polgreen Bridgetower, Gower Place, Euston Square [London] - September 22, 1815]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/160cvdnd2v-cor.
Chicago
Wesley, Samuel, 1766-1837, Letter from Samuel Wesley to George Augustus Polgreen Bridgetower, Gower Place, Euston Square [London] - September 22, 1815, September 22, 1815, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/160cvdnd2v-cor.