Robert H. Schuller (1993). “Robert H Schuller: The Inspirational Writings : Tough Times Never Last, But Tough People Do/Tough Minded Faith for Tender Hearted People”, Bbs Publishing Corporation
Saint Augustine of Hippo, Saint Augustine, Thomas A'Kempis (2006). “The Confessions of St. Augustine, Including the Imitation of Christ”, p.312, Cosimo, Inc.
Robert H. Schuller (1993). “Robert H Schuller: The Inspirational Writings : Tough Times Never Last, But Tough People Do/Tough Minded Faith for Tender Hearted People”, Bbs Publishing Corporation
Joseph Hall (1867). “Devotions, Sacred Aphorisms and Religious Table Talk: Selected from the Writings of the Eminently Pious and Learned Bishop Hall ; to which is Prefixed a Brief Memoir of the Author”, p.396
Robert H. Schuller (1993). “Robert H Schuller: The Inspirational Writings : Tough Times Never Last, But Tough People Do/Tough Minded Faith for Tender Hearted People”, Bbs Publishing Corporation