Fritjof Capra (2010). “The Tao of Physics: An Exploration of the Parallels Between Modern Physics and Eastern Mysticism”, p.174, Shambhala Publications
Robert Murray M'Cheyne, Andrew Alexander Bonar (1852). “Memoir and remains of the rev. Robert Murray M'Cheyne, minister of St. Peter's church, Dundee”, p.244
Charles Haddon Spurgeon (1988). “Spurgeon at His Best: Over 2200 Striking Quotations from the World's Most Exhaustive and Widely-read Sermon Series”, Baker Publishing Group