MLA
Wesley, John, 1703-1791. Letter from John Wesley to "My Dear Brother," [unaddressed], Birmingham - August 7, 1787. August 7, 1787. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/99351c5bh7-cor.
APA, 6th edition
Wesley, John, 1703-1791. (August 7, 1787)[Letter from John Wesley to "My Dear Brother," [unaddressed], Birmingham - August 7, 1787]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/99351c5bh7-cor.
Chicago
Wesley, John, 1703-1791, Letter from John Wesley to "My Dear Brother," [unaddressed], Birmingham - August 7, 1787, August 7, 1787, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/99351c5bh7-cor.