MLA
Wesley, Charles, 1757-1834. Letter from Charles Wesley junior to Sarah Wesley - December 28, [No Year]. December 28, year unknown. Wesleyana Collection. Pitts Theology Library. https://digital.library.emory.edu/purl/948sbcc30n-cor.
APA, 6th edition
Wesley, Charles, 1757-1834. (December 28, year unknown)[Letter from Charles Wesley junior to Sarah Wesley - December 28, [No Year]]. Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/948sbcc30n-cor.
Chicago
Wesley, Charles, 1757-1834, Letter from Charles Wesley junior to Sarah Wesley - December 28, [No Year], December 28, year unknown, Wesleyana Collection, Pitts Theology Library. https://digital.library.emory.edu/purl/948sbcc30n-cor.