Smith Wigglesworth (2016). “Smith Wigglesworth on Manifesting the Power of God: Walking in God's Anointing Every Day of the Year”, p.50, Destiny Image Publishers
Florence Nightingale, Michael D. Calabria, Janet A. Macrae (1994). “Suggestions for Thought by Florence Nightingale: Selections and Commentaries”, p.114, University of Pennsylvania Press
Oswald Chambers (2015). “Biblical Ethics / The Moral Foundations of Life / The Philosophy of Sin: Ethical Principles for the Christian Life”, p.84, Discovery House