John Newton (1847). “One Hundred and Twenty Nine Letters from the Rev. John Newton ... to the Rev. William Bull, of Newport Pagnell: Written During a Period of Thirty-two Years, from 1773 to 1805 ...”, p.5
John Newton, Richard Cecil (1824). “The Works of the Rev. J. Newton ...: With the Memoirs of the Author and General Remarks on His Life, Connections, and Character”, p.142